LPS 9.3.2 Now Available!

I'm pleased to announce that our new LPS 9.3.2 service pack is now available.  This isn't a major release, but it does contain a number of enhancements.  In particular we've focused on LPS Core and enabling defense-oriented workflows throughout the software suite.  

The new release can be accessed via your local distributor or if you are in an area where we sell direct you may download it from our Support site: just login and navigate to "Fixes and Enhancements" on the left and then select "LPS 9.3."  The installer also includes the ERDAS IMAGINE 9.3.2 release as well.   

Here's a summary of the new features and benefits:

LPS Core

• Significantly improved the performance of the following processes for any image that uses a Mixed Sensor geometric model.

   - Ortho resampling using Mixed Sensor in LPS

   - Ortho resampling using calibrated images with Mixed Sensor in Geometric Correction

   - Display of calibrated images with Mixed Sensor in Viewer (with “Orient Image to Map System” on)

• Extended the preference that controls the display of the full file pathname to apply to all pick lists and cell array interfaces where the full file pathname displays.

• Added a preference to force constraints on tie points that have a very narrow ray convergence.

Stereo Point Measurement/Classic Point Measurement

• Added “Force North-up” icon to the viewer. This new feature rotates all images to North-up direction and makes it easier to locate similar areas or common points.  

• Added a “View” tab on the Properties dialog that allows you to maintain the same scale factor over all images.  This way images with different native scales will be displayed in the same map scale.

• Added an option in SPM to choose to display either image coordinates or ground coordinates in the status bar.

Automatic Terrain Extraction

• Added “Threshold to compensate for relative rotation of image pairs to improve ATE results” preference. This preference improves ATE results when image pairs have an uncommon relative image rotation by eliminating holes or blunders.

ImageEqualizer

• Added a "save" capability that stores the image's statistic data with the images and loads it automatically when you reopen the project.

ERDAS MosaicPro

• When exporting seamlines from MosaicPro, those shapefiles now contain additional information stored as attributes. These attributes include the image name and acquisition date and time. This makes it easier to relate a seamline to the image from which it was derived. The output shapefile is consumed by the IMAGINE RPF exporter when making CIB to automatically drive output product values.

• A new feature in MosaicPro extracts the image acquisition date from image metadata (when available) and allows you to sort images based on acquisition date.  Now you can sort images for mosaic priority with the most recent on top. You can also enter or edit the date in the cell array and revise the order. Search for "Sort Images" in the online help for complete instructions on

this new feature.

PRO600 & PRO600 Fundamentals

• A new tool for collecting object height-annotated symbols

• New PROLPS driver options to automatically disable AccuDraw and AccuSnap

• Support for PRO600 for SOCET SET 5.4.2

Defense Productivity Module

Sensor Models

• Significantly improved the performance of the followingprocesses for any image that uses the CSM geometric model. This includes the MC&G model.

o Ortho resampling using calibrated images with CSM in Geometric Correction.

o Display of calibrated images with CSM in Viewer (with “Orient Image to Map System” on).

Image Slicer

• Significantly improved the segment footprint computation when using a terrain file.

Precision Ellipse Generation (PEG) Tool

• Added a tool to support precise computation of the error ellipse for an RPC image/DTED intersection. The resulting ellipses display in the Viewer and graphically show the confidence in the reported position of a given point location. You can export these ellipses to fully

attributed 2D or 3D shapefiles.

Photogrammetry Meets Kite Aerial Photography (KAP)

Kite Aerial Photography, as the name suggests, involves rigging a camera up to a kite system and then using it to take aerial photographs. After seeing my previous post on photogrammetry with a camera attached to a helium-balloon, Dr. Mike Smith at Kingston University contacted me about research he has been conducting in the realm of KAP and photogrammetry. Along with Drs. Chandler and Rose, he recently published a paper in Earth Surface Processes and Landforms entitled "High spatial resolution data acquisition for the geosciences: kite aerial photography".

The paper is relevant for the mapping industry because it provides an overview of the aerial acquisition process, the photogrammetric processing, and then an accuracy assessment of the results. I'll start with the results: their methodology enabled the production of stereo pairs, digital elevation models, and stereo imagery. Furthermore, the stereo imagery was triangulated with an accuracy of roughly 10mm in planform against surveyed ground control points.


The methodology involved using a 6 megapixel Nikon D70 camera and collecting aerial photography at altitudes of up to 200 meters over three test sites in the UK. GCP targets and XYZ samplings for topographic modeling were measured with Leica Geosystems TPS1200 and TCA 1105 Total Stations.

All the photogrammetric processing was performed in LPS. This involved setting up an LPS Blockfile (a project file), adding the images, and subsequently running through the aerial triangulation process in LPS Core in order to produce stereo pairs. With oriented images, the LPS Automatic Terrain Extraction module could be used to generate a digital elevation model. Next, the oriented images along with the digital terrain could be used to produce digital orthophotos. The paper describes the process in a high level of detail, as well as an excellent evaluation and discussion of the results.

Here is an image of an orthophoto superimposed with terrain points (red = automatically extracted, blue = measured via total station):

And here is a perspective view of an orthophoto draped over a corresponding digital elevation model, with contours:
In my opinion it is a great looking product considering it was generated with a 6 megapixel SLR camera flown from a kite!!

So why is this relevant for the mapping business?

The study illustrates a great low-cost approach to localized (as opposed to wide area) mapping, which means it may very well be a viable option for applications ranging from mapping cultural heritage sites to localized studies on soil erosion and other environmental and natural resource mapping projects. It is significant because it represents a significant cost saving over the traditional helicopter-based approach. If I had any talent for flying big kites I'd give it a whirl, but for now I'll leave it to he pro's...

Update: Photogrammetry at the Acropolis

Last July I stumbled across a laser scanning and photogrammetry operation during a visit to the Acropolis in Athens, Greece. As discussed here, the project involved terrestrial laser scanning coupled with aerial photogrammetry. A unique aspect of the project is that airspace restrictions over the Acropolis meant that imagery could not be collected by motorized aircraft (e.g. helicopter), so the project team rigged up a balloon system instead. Here's a picture of the balloon and camera in flight:


A paper describing the data collection and processing process is now available online here. The paper is an excellent resource for those interested in digital preservation of cultural heritage sites, and also outlines how complementary photogrammetry and laser scanning are for 3D data generation. As is the case with many photogrammetric projects, the digital orthophotos derived from the aerial photographs will ultimately reside in a GIS.

Innovative Applications in Photogrammetry

If you have been to the ERDAS home page lately you may have seen the "Top 10 Reasons to use..." lists for IMAGINE and LPS. While thinking about the "Top 10 reasons to use LPS", I also researched innovative uses of LPS and photogrammetry in general. I have listed some of the most interesting applications that I have come across below. Note that the list below is LPS-centric, although many of these applications used a mix of tools. I believe the list illustrates how useful and flexible photogrammetry is as a tool for any 3D geoinformation research.

So here is an alternate list outlining 10 innovative photogrammetric applications (in no particular order):

• Reconstructing Aboriginal rock art. LPS was used to extract digital elevation models (DEMs) and orthophotos.
  

• Illustrating the changing landscape through historical aerials on the Internet. Since 2004, NETR Online estimates that they have orthorectified approximately 100,000 historical images using LPS. With the advent of historical imagery in Google Earth as well, I think the time has come when people not only want a
  

• Determining the state of glaciers and forecasting the impact of climate change. LPS was used to generate a DEM in the Tien Shan range in Kyrgyzstan, using ASTER data and Ground Control Points (GCP) collected from the topographic maps.
  

• Measuring the impact of selective logging on tropical forests in the Congo. LPS was used to georeference imagery and create a seamless image mosaic.
  

• Studying Medieval Architecture. LPS was used to generate and analyze 3D models from stereo imagery to examine the metrology and proportional systems used in the design of Irish ecclesiastical architecture.
  

• Mapping unplanned development to preserve the environment and manage growth. All the photogrammetric tasks where done in LPS, including automatic digital surface model (DSM) extraction.
  

• Historically representing a Macedonian Palace. The photogrammetric image processing of the data, including of the tie point measurement, bundle adjustment, DSM and orthophoto generation was done in LPS.
  

• Producing Orthophotos in the Himalayas. Acquiring stereo imagery from remote/inaccessible areas can be difficult and expensive. LPS was used to produce orthos from a single image.
  

• Creating terrain models of a meteorite crater. LPS was used to extract a high resolution terrain model from a stereo pair of images acquired from the QuickBird satellite.
  

• Mapping Landslide Debris. LPS was used to rectify ortho-images and extract terrain in a study based on a 1999 earthquake in China.

3D City Modeling

I'll be hosting a webinar on December 9th entitled: "3D City Construction Workflows: From Collection to Presentation". This will be an opportunity for us to explore workflows for planning projects and developing 3D building content data, which can then be fed into various GIS and mapping applications. We'll also take a look at data presentation: methods for visualizing and sharing the data.

3D city modeling is a rather nebulous topic, and there are many ways to create 3D city models. Here are a few different options:

- Automatically extruding 2D building polygons digitized from an ortho, either from a rooftop Z value or guesstimating the height. This is the "quick and dirty" method.
- Manually model each building individually and tag it with an XY location (often guesstimating the spatial dimensions). These models may be based on ground photos, oblique imagery, or a combination.
- Photogrammetrically measure and extrude buildings.
- Photogrammetrically measure and extrue buildings, and then model further detail and add elements such as photo-texture.

The webinar will primarily focus on the 3rd option: using photogrammetric tools to measure buildings. In addition to the actual extraction process, other discussion points such as data capture, data quality, accuracy, and other topics will be outlined as well.

If you're a GIS/photogrammetry/mapping professional, please tune in to one of the scheduled webinars. You can sign up here.

LPS 9.3.1 Now Available!

We've just released our first Service Pack for LPS 9.3, called LPS 9.3.1. It is available from our support site and is located in the "Fixes and Enhancements" section. In addition to numerous bug fixes, LPS 9.3.1 (which is a shared Service Pack with ERDAS IMAGINE) also contains the following features and improvements:

LPS Core

• Added required entry of Average Terrain Elevation when creating a block file for Orbital Pushbroom sensors. This entry overrides the generally less accurate method of using the sensor metadata to derive a mean elevation.

Stereo Point Measurement/Classic Point Measurement

• Improved and simplified image loading.
• Added “Create Ground Control Point” feature that calculates 3D ground coordinates from image points which are measured in at least two images. This is particularly useful in transferring control points from more accurately oriented imagery into lower accuracy imagery.
• Improved several icons to maintain consistency with other dialogs in LPS and IMAGINE.
• Improved image tracking to use the mouse wheel to adjust the image positions in relation to each other and remove the x-parallax.

RPC Generation

• Added fields to give the user the ability to control parameters of the RPC fit cube. This can help improve the fit accuracy.
• Added an option to output a report file that shows where higher residuals are falling, check point and fit point statistics, and other information that help to refine the results on subsequent generations.

LPS Core Triangulation

• Improved RPC refinement by automatically detecting points with parallel rays and using these parallel rays as an additional constraint. This eliminates the need to manually delete points with no convergence.

ERDAS MosaicPro

• Improved memory management during Image Dodging and seamline generation.
• Faster seamline refreshing after editing and undo.
• Improved performance when running MosaicPro with a shapefile or an AOI with multiple polygons as a single output mosaic.

Defense Productivity Module

Image Slicer

• Added capability to input active area.
• Named all segment IDs from West to East regardless of how images were captured.
• Improved quality of segment boundary computation.
• Added an option to trim the nonoverlapping portions of the stereo segment image pairs.
• Changed the pyramid generation so it is driven by the IMAGINE preferences rather than always making pyramids after segmentation.

TFRD AMSD Calibrator

• Eliminated requirement that LPS be installed to generate an Image Slicer project file (.isproj).
• Added an option to output the rectangle and stereopair accuracy values from AMSD to a text file.

IMAGINE Radar Mapping Suite

• You can now use the Subset Processing Step to extract portions of the input images in InSAR from which to generate a DEM.
• Multilook factors are now displayed directly on the Reference DEM Processing Step of InSAR.
• Coherence window values are now edited within the Interfere Processing Step of InSAR, and a working Coherence image is generated and available for viewing.
• The Register step in InSAR has been renamed Coregister in which the match image is coregistered to the reference image.
• In the Coregister step, there are now two tabs named Coregistration Input Parameters and Coregistration Output Coefficients. The Coregistration Output Coefficients tab contains a CellArray reporting polynomial coefficients which describe the pixel shift of the match image along the x-direction and along the y-direction.
• In the Height step of InSAR, you can now select an interpolation method for the resample process as part of the chosen rectification method.

ERDAS IMAGINE – General

• Chooser icons, such as those for selecting colors or Annotation styles, now have two portions. Click the top portion to open the Chooser dialog directly; or click the bottom portion to open the selection menu as before.

IMAGINE GLT

• GeoPoint Annotation has a new Properties dialog where you can select a template for the text to be displayed. You can also configure options indicating where the label is to be placed and whether or not there is a leader line from the label to the point. The text template can be a dynamic coordinate (as before), an incrementing number, a static string or a combination of coordinate or incrementing number and static string.

IMAGINE Viewer

• In addition to the Annotation Alignment tool, the Annotation menu and tool palette now contain separate options for aligning annotation vertically or horizontally.
• You can now save a Footprint layer in the Viewer/GLT as Annotation or as a shapefile.

IMAGINE Composer

• Leading zeros are now displayed for coordinates in Grid/Ticks.
• You are now able to specify the text to be displayed for the units in an Annotation Scale Bar.
• When generating an Annotation Grid/Tick, you can now specify a rotation angle for the coordinate labels.

How to Access and Download LPS 9.3 and other ERDAS Software

I've received a lot of questions from people asking about how they can access and download the new LPS 9.3 release. Since we've changed the methodology for software access, I've outlined the new procedure below. This example covers the download process for LPS 9.3, but it essentially the same for all the products on our new web-site.

The first step is to go to the Product page of the software you would like to download. For LPS, this is here. Note that all the products can be accessed by the product page, and are organized into general functions: Author, Manage, Connect, and Deliver. Clicking on a cube (e.g. Author) at the top will filter the product list.
Next, click the downloads tab on the right-hand side of the tab list.

After clicking the download tab, the content will change and you'll see a download link. After clicking on this you will be directed to log in. Please note that this log in only pertains to software download access, and you will have to register with some basic details.

After registering, an email is sent with your login details. After you login, you can go to the product download tab again and click on the download link once again. For LPS you will see a message saying that due to the large file size (~600MB for LPS) a temporary ftp login has been created for you and that you will be emailed the ftp location and login details. The email is sent immediately and you should receive it within seconds of hitting the download link.

Next, log on the the FTP site and download the software. Without a license LPS will work in "demo mode" for 30 days, but you can also contact your local representative for an evaluation license (or any questions). You may also contact your local representative for the software package on DVD.

Now Released: LPS 9.3

We are pleased to announce the release of LPS 9.3 today! This is a major milestone for ERDAS, as we're launching new releases across all product lines today, which is a first. Additionally, we've completely updated the website at www.erdas.com. Each product can be downloaded from the site from the various product sections via the "Downloads" tab. For LPS 9.3, go here and click on the Downloads tab. Note that you'll need to register to access the download. You can also get a new 9.3 license from the link on the www.erdas.com front page.


The main theme of the LPS 9.3 release is 3D feature extraction, with the introduction of "PRO600 Fundamentals for PowerMap XM": PRO600 Fundamentals is a streamlined stereo feature extraction software. Basically we've made PRO600's PROCART module (3D feature extraction) available for Bentley PowerMap XM, which is a GIS-oriented application for map production in a 2D or 3D environment. PRO600 Fundamentals also includes LPS Stereo.

I wrote about a couple of the new benefits in previous posts, but I've also included the entire list of improvements below.

In LPS Core, the following improvements have been added:

• Export to KML: This new LPS 9.3 feature exports an LPS block file or group of block files to the KML (keyhole markup language) file format. This feature allows for the export of both image footprints as well as point measurements associated with the block file.
• Improved Automatic Point Measurement (APM) point correlation quality in cases with less than 50% overlap, variable flying height, and in sidelap areas.
• Added support for NITF NCDRD format in the orbital pushbroom QuickBird/WorldView model.
• The Triangulation Point Review user interface has been extended to support Satellite Sensor Models.
• New Support for Image Chipping for NCDRD Sensor Model.
• Registration free .NET and COM: New Registry Free LPS allows users to install different versions of LPS on the same machine.
• Synchronized units of measure for the Average Flying Height (Frame Camera) and Average Elevation (Orbital Pushbroom) defined in the Block Property Setup with the units reported in the block file.
• The Average Elevation, Minimum Elevation and Maximum Elevation units in RPC Model projects are now displayed in the project vertical units in the Frame Editor.
• Synchronized units of measure for GCPs and residuals in the Refinement Report.
• Enhanced Importer for ISAT projects with multiple flight lines.
• Support for EMSEN Hand Wheels.
• Added the LHN95 Geoid model (Switzerland).
• Added Latvian Coordinate System (LKS-92) support, which includes the Latvian Gravimetric Geoid (LGG98).

LPS Automatic Terrain Extraction (ATE)

• DEM Accuracy: Added an option to enter a tolerance in the vertical units of the terrain source to set the accuracy range for the predicted surface value of the area. The Min and Max Z Search Range will change with respect to the accuracy value entered. Providing a reliable tolerance will result better matching quality.
• Added support for all currently supported sensors in Adaptive ATE (not just frame cameras and ADS sensors).
• Reliability has been improved with better memory handling.

LPS Terrain Editor

• Drive to Control Point: In 9.3 a new panel in Terrain Editor enables the display of GCPs and tie points associated with the currently loaded block file. An additional new dialog called “Control Point Display Settings” allows users to filter points in the cell array and choose the rendering settings for the Ground Control Points panel. The user can load some or all of the image pairs that a GCP is projected into. This new tool lets users check the quality of the DTM with respect to GCP, check points and the tie points. This tool can also be used for visual inspection of triangulation results after a bundle block adjustment.
• Post Editor hotkeys: allow a user to quickly move through points by using keyboard arrow keys and adjusting the Z value for selected points in gridded terrain files.
• Enhanced jpeg image display.

ERDAS MosaicPro

• Save to Script Functionality: With the release of LPS 9.2, users were able to batch script the entire MosaicPro process and then execute the script from an MSDOS prompt. In 9.3 it is possible to generate the batch script automatically from the MosaicPro user interface. The script generated from MosaicPro may also be used as a template which can be easily modified. This new feature builds a script file from a combination of the currently open MosaicPro project and/or from previously saved settings from image dodging, color balancing, seam polygons, and exclusion areas. The MosaicPro process can then be run in time-set, batch mode from the MSDOS prompt.
• Improved performance for seam polygon generation with "most nadir", "geometry", and "weighted" options.
• Various reliability improvements.

STEREO ANALYST for ERDAS IMAGINE

• Extend Features to Ground: this new feature uses a 3D Polygon Shapefile and extends the segments of each polygon (as faces) to the ground to form solid features (e.g. Buildings).

PRO600

• Ability in PRODTM for the user to specify the extent within which to load terrain data. This allows very large terrain datasets to be used in PRODTM, in a piece-wise manner.

ORIMA

• For triangulation projects using AD40 data, multiple ADS40 flown at the same time are now supported. This required the change of some file formats. This new approach leads to shorter project creation times.

• CAP-A Release 8.10: New Handling of Orientation Data for ADS40. This new data handling has two primary advantages:

o The amount of disk space to store the project is drastically reduced.
o The startup time of CAP-A is much faster as there is no need to read the *.ori files and find the corresponding orientation for each point.

Defense Productivity Module (DPM)

• Users in classified environments can now process NGA MC&G imagery in LPS photogrammetric workflows if the DPM is installed. This support includes access to AMSD ground and imagery points.
• A new Image Slicer has been created to facilitate cutting of the original imagery into smaller segments for extraction. After slicing, an RPC model may be generated to provide support in ERDAS products without a local DPM license. If an NITF module is licensed, the RPC segments may be exported to NITF with RPC00B tags for interoperability with a wide variety of software packages.

LPS 9.3 Preview: Control Point Review Tool

Last month I highlighted the ability to export LPS Block Files to KML. I'll do a full round-up of the new functionality as soon as we release, but for today I will focus on another new feature: Ground Control Point Review in the LPS Terrain Editor module.

The background for this feature came from many requests we received for the ability to review points either by themselves in stereo or as a means of checking terrain accuracy. Thus, we added a new panel in the Terrain Editor "View" drop-down menu: View > Panels > Ground Control Points.

In the screen capture below, I have launched the Terrain Editor and have opened the GCP Review Tool. I haven't loaded any imagery. The GCP Review Tool automatically loads in all points (ground control points and tie points) from the Block File that the Terrain Editor was launched from. You can see from the column settings that it provides some basic information such as ID, point type, coordinates, the number of images the point intersects, and the description.

In the Terrain Editor, the usual method for loading stereo pairs is to drag and drop them from the image pair list (on the left above) into the stereo viewport. One of the nice features of the GCP Review Tool is that you can automatically load images by double clicking on a particular point (double-click anywhere on the row). This is beneficial because it removes the need to know exactly which stereo pair to pick when you would like to review a particular point. In the screen capture below, I loaded a stereo pair associated with Point ID 30 by double-clicking on it. You can see that this is a full GCP, and it is even possible to see the target in the imagery.

Point symbol and label graphics can be turned on or off by using the icons on the bottom left of the panel. Additionally, the "Settings" button can be used to modify the behaviour of the tool. For example, it is possible to filter the points (e.g. only display full ground control points). It is also possible to customize the graphics (size, color, and label font).

ERDAS UK GeoImaging User Group Conference 2008

If you're in the UK you may be interested in checking out the GeoImaging User Group Conference 2008 hosted by InfoTerra. The event is in Oxford on September 29th and 30th and will cover the entire range of ERDAS desktop and enterprise products.

I will be there on the 29th to deliver a presentation on our photogrammetry product line. The main focus will be on the upcoming LPS 9.3 release, but I'll also cover productivity tips, photogrammetric workflows, and highlight the directions we're going in. Please feel free to sign up and attend if you are in the region!

Upcoming GeoEye-1 Satellite Launch

The GeoEye-1 satellite launch on September 4th has been getting a lot of media attention lately. Instead of regurgitating the specs, I'll focus on a few other details.

First of all, check out the Launch Site here. It has a count-down and informs us that there will be a live video stream of the launch - should be interesting to watch.

There were several reports today about a deal between GeoEye and Google, whereby Google will be the exclusive online mapping site with access to the imagery.

Note that LPS will support both the rigorous and RPC models for GeoEye-1 in both LPS 9.2 (the current version) as well as LPS 9.3 (coming soon, stay tuned).

What's New in LPS 9.3 Webinar

You should be seeing a press release on www.erdas.com shortly, but I wanted to highlight the fact that we are planning a webinar on the new release next week. While we just released LPS 9.2 earlier this year, the LPS 9.3 release is now in beta and we are looking forward to getting it on the market soon.

I highlighted one of the new features, KML Export from the LPS Block File, in a previous post. The webinar will proceed to highlight the new enhancements and solutions, as well as a live demonstration of certain capabilities.

Anyways, you can check for more details including registration for the free webinar on the ERDAS site in the next 24 hours.

LPS 9.3 Preview: KML Export

We're getting late in the release cycle for the upcoming LPS 9.3 release (the beta testing phase has now started!) so I thought I'd start previewing some of the new functionality we're releasing.

An increasing number of geospatial applications are supporting KML (although the word "support" can mean a lot of things), so mentioning that we'll be able to export the LPS Block File as a KML file isn't earth-shattering news. However, KML in the context of photogrammetric applications is relatively new and there are some interesting implications.

First I'll show how the exporter works and then get into what some of the uses are. Here's a screen capture of a small photogrammetric project in the LPS Project Manager, in area of Waldkirch, Switzerland.As you can see it is a relatively "complete" project. There are triangulated images, GCPs and Tie Points, some DTMs, and orthophotos. From the Project Manager, we have a new drop down entry in the "Tools" section called "Export to KML". Click on this and the following dialog appears.The dialog allows you to choose which elements of the photogrammetric project (Block File) you would like to export. Check the various boxes and then you can hit the "Export" button to generate the KML file.

For this dataset I've uploaded the output KML file here. Feel free to download it and check it out. Note that the various photogrammetric data elements (e.g. Ground Control Points) can be turned on and off. Here is a screen capture of the file in Google Earth.
So this brings us to the question, why is this relevant? The first thing that comes to mind is project tracking and status reporting. Photogrammetric/mapping projects are increasingly completed in disparate geographic areas. This can make project tracking a challenge. While there's a mixed-bag of current approaches to project tracking, a KML file can provide a relatively compact (especially if you leave out the tie points) and visual representation of what parts of the project are complete. For example, an organization with an office in the USA that is working with a partner in another part of the world could request daily updates of status for a large digital ortho project. By looking at the "orthos" layer, the project coordinator could not only see how many are complete (like they may currently do with MS Excel or other spreadsheet apps) but also see a visual of the completed project areas. Thus, they could see if the "challenging" parts of the project had been tackled yet (e.g. rugged terrain or urban areas) and manage accordingly.

I'll talk about this a bit more in future posts, as well as hightlight some of the other solutions we've been working on this year. We're certainly looking forward to getting the new release out!

Upcoming ERDAS Webinar: Mosaicking

I'll be doing a webinar next week on mosaicking, which was just announced on the ERDAS web-site yesterday. The main focus will be planning considerations for frame photograph mosaicking, processing techniques (radiometry, image manipulation, seams, output considerations), and final mosaic product generation. This may be of interest to both LPS and ERDAS IMAGINE users (along with anyone generally interested in mosaicking), since I'll be using MosaicPro for the processing: an add-on module to both LPS and IMAGINE.

The registration page is here. We'll be hosting the webinar at both 3AM and 11AM EST, so please feel free to join us for either session!

Photogrammetry at the Acropolis

After a few weeks offline I'm now back and writing from Liege, Belgium. During my time off I had the opportunity to visit the Acropolis in Athens, Greece. While walking up to the Parthenon I noticed there was a terrestrial laser scanner set-up and operational - although unfortunately I didn't get any photos. But that was enough to get me wondering what the project was about. At the top of the Acropolis I found a sign with a short description of the project (photos below). Since it is difficult to read I have reproduced the text below:

DATA ACQUISITION FOR THE PHOTOGRAMMETRIC RECORDING OF THE ACROPOLIS

The Acropolis Restoration Service carries out the project of geometric documentation of the Acropolis hill, the circuit Wall and the Erechtheion, using photogrammetric methods together with 3-dimensional scanning.

All the information to emerge is to be entered in a Geographic Information System (G.I.S) that will be available through the Acropolis Restoration Service's web site (ysma.culture.gr).

Photogrammetry at the Acropolis was also a subject of discussion at the recent ISPRS Conference in Beijing. One of the technical sessions (TS-SS19) was "Recording and Documenting the Acropolis of Athens - From Classical Ancient Greece to Modern Olympics". While I wasn't at the conference, a colleague sent me the paper for "Recording, Modeling, Visualisation and GIS Applications Development for the Acropolis of Athens", by Tsingas et al. The paper discusses the various techniques employed by the project outlined above, which include geodetic field measurements, terrestrial scanning, and photogrammetric data capture and processing. Of the many data products to come out of the project, an interesting one is a top-view orthomosaic with a 10mm resolution. A 22MP camera was used on a balloon system, as motorized vehicles such as helicopters are not permitted to fly above the Acropolis. Also of interest (and news to me) is that Leica Geosystems is a partner in the project. One of the terrestrial scanners is a Leica HD3000, while ERDAS LPS is used for parts of the photogrammetric processing. This included camera calibration, bundle adjustment, and terrain processing.

The paper describes the methodology in detail, and I will see if it is available online anywhere - it provides an excellent discussion of various techniques used in concert to fully capture a highly detailed digital version of the monument. A few other good papers on photogrammetry/mapping at the Acropolis are here and here.

Cell Arrays in LPS

In LPS we use a spreadsheet like tool called a “Cell Array” for managing and manipulating data in several parts of the software package. The first place you see a Cell Array is when you load a project in the LPS Project Manager: it is the list at the bottom with one row per image. Generally Cell Arrays are used for different purposes in the various places they are embedded, so I will highlight a few of them here.

In the LPS Manager, the Cell Array lists all the images and also provides an image-by-image status. There are status columns (either red for incomplete or green for complete) for Pyramid Layer, Interior Orientation, Exterior Orientation, if there is a DTM associated with the image, an Ortho associated with the image, and whether the image is “online”. That is, does the image reside where the blockfile has referenced it. There is also an “Active” column that flags each particular image for inclusion in various processing operations (e.g. running pyramid generation or APM on just the active images). From the Cell Array you have the ability to select images, perform a criteria selection, and delete the selection (remove images from the project).

One of the powerful capabilities is to use the criteria selection plus the “formula” option to activate or deactivate images. A trick here is to use the criteria selection to select a group (e.g. Image ID > 30) and then activate or deactivate your selection group using the “formula” Cell Array option. Once you have a selection set, right click on the “Active” column heading and choose the “Formula” option. Type in “1” and hit Apply to activate all the images. Likewise you can type in “0” and hit apply to deactivate all the selected images (see the screenshot below).

Another place with a Cell Array is the Frame Editor. When you are in “Edit All Images” mode, the image, sensor name, orientation parameters and other information are all made available in the cell array. This is a useful place for setting the image orientation status. For example, if you want to import orientation parameters from GPS/IMU data you can cut and paste the six parameters in, set the status to “fixed” and immediately view the images in stereo (assuming there aren’t any issues with the orientation parameters). It is also possible to Import and Export data (among other things) by right clicking on the column heading. For example, orientation parameters can be exported by selecting the images, highlighting the headings for the orientation parameters, then right-clicking on the column heading and choosing "export". See the second screenshot below for an example.

A Cell Array is included in the LPS Stereo Point Measurement tool as well. This Cell Array can be useful for managing tie and control points. By saying “managing”, I mean performing tasks such as:

• Importing GCP points
• Exporting tie points
• Defining the point status
• Activating and Deactivating points
• Deleting points

For example, if you ran Automatic Point Measurement and then proceeded through triangulation, you can export your tie points as XYZ data and then use that as the basis for a “quick and dirty” surface model. Automatic Terrain Extraction is a better choice (where you can use tie and control points as seed data), but at least this allows you some flexibility.

LPS Terrain Editor: Terrain Editing Tip

For today's post I thought I would share a tip for a method of quickly editing TIN terrain datasets in LPS. In the LPS 9.2 Terrain Editor, we added a new "Terrain Following Cursor" mode. This was added as an icon in the Terrain Editing panel:Here's how it looks in the panel:
The terrain following cursor snaps the floating cursor to the height of the terrain for whatever XY location you move the cursor to. It operates in either an "on" or "off" mode, so you can easily roam around your imagery and the Z value (height) of the floating cursor will adjust automatically based on the terrain.

So why is this important?

Because it allows you to remove erroneous elevation spikes very quickly! When used in conjunction with the "Delete Tool" you can quickly identify points that are off the ground and delete them, or alternatively adjust them to their correct height. You can use the Terrain Following Cursor mode with any edit tool - here it is while using the delete tool:This means you can use it to easily locate problem areas such as the one below. See how the post is off the ground - the elevation of the point is 551 meters, when it should be at 569 meters.
Here's what the surface looks like after removing the post (a single-mouse click). This can be quite useful as a quality control tool - perhaps after completing area editing operations. After deleting posts, the floating cursor snaps back down to the surface. This allows you to quickly maneuver through a scene removing (or adjusting) TIN mass points. On a final note, you can even map Terrain Following Cursor mode as an event on your input device (e.g. middle-mouse button, or a Topomouse button).

Historic Aerials: Visualizing Change Over Time

There's been a fair bit written on Historic Aerials already, but check out the new article in V1 Magazine. I've been a fan of Historic Aerials site for awhile now, and a few weeks ago we had a chance to interview them. A lot of the comments from the discussion are encapsulated in the article, and overall it was quite interesting to hear Jim and Brett talk about the trials and tribulations of working with historic photography. They are heavy LPS users (mainly for orthorectification and image processing) and have processed massive quantities of orthos while building content for the site.

It's easy to spend a lot of time on the site: if you want to see a good example of suburban Atlanta's development check out our ERDAS office location:

5050 Peachtree Corners Circle, Norcross GA. There's imagery from 1955, 1960, 1972, 1978, 1988, 1993, and 2007. When looking at the older images it becomes apparent that the entire area was developed over the past 20-30 years.

Make sure you check out the "Compare Two Years" option as well - it allows you to compare a second year to your currently loaded year and then adds a "swiping" capability to the viewer. Very cool!

LIDAR and Imagery Collection for Rapid Response Mapping

At our ASPRS UGM last Tuesday I presented a case study on rapid response mapping. The case study was an interesting application, so I thought I would share it here as well. The focus was on a joint ERDAS (software) and Leica Geosystems (hardware) exercise conducted last summer called "Empire Challenge 2007". This was joint military exercise for testing intelligence, surveillance and reconnaissance (ISR) concepts. The exercise was initially developed after technical issues were identified in sharing ISR information between allies in hotspots such as Afghanistan. I wasn't personally at the event, held near China Lake (California), but did get a chance to work with some of the data that was collected.

For the ERDAS/Leica team, the exercise involved flying a Cessna 210 mounted with both LIDAR and optical sensors over a project area and then creating final data products immediately after downloading the data. The team spent approximately three weeks on-site, and during this time they worked in three project areas and were able to fly, collect, and process a few thousand images and a massive quantity of LIDAR data.

The hardware consisted of an ALS50 (LIDAR), the soon-to-be-released RCD105 digital sensor, as well as Airborne GPS/IMU, a GPS Base Station, and some data processing workstations. While not officially released by Leica, the RCD105 was first "announced" at last years Photogrammetry Week in Stuttgart, Germany. More specifically it was discussed in this paper by Doug Flint and Juergen Dold. It is a 39 megapixel medium-format digital camera - which makes for a great solution when coupled with the ALS50 airborne LIDAR system. Here is an image of the RCD105:The software mix covered several areas. These included:

• Flight planning and collection software (FPES and FCMS)
• LIDAR processing (TerraScan)
• GPS and IMU processing (IPAS Pro, IPAS, CO, and GrafNav)
• Image processing (ERDAS IMAGINE)
• Photogrammetric Processing (LPS, ERDAS MosaicPro, ERDAS ImageEqualizer)
• Quality Control (ERDAS IMAGINE)
  

There were three main missions that were flown. These included:

• A basemap collection flight. At 3048 meters, this was the highest altitude flight. The imagery GSD (Ground Sample Distance) was 0.3 meters. Data products included an orthomosaic, georeferenced NITF (National Imagery Transmission Format) stereo pairs, NITF orthos, a LIDAR point cloud, and a LIDAR DEM.
• A tactical mapping mission. This was a lower altitude flight (914 meters) collecting imagery at a GSD of 0.06. This was "tactical" as it covered specific project areas - as opposed to the broad swath of data collected from the higher altitude basemapping flight. Data products included an orthomosaic, geoferenced NITF steree pairs, NITF orthos, and a LIDAR point cloud and DEM.
• An IED corridor mission: basically covering a linear feature (a road). This was the lowest altitude and highest resolution flight (at 305 meters and 0.04 GSD), which produced NITF stereo pairs, NITF orthos, as well as a LIDAR point cloud and DEM.

The project area was pretty typical inland Southern California scrub/desert. Here's a photo from the ground:

And here's one of the images (in this case shown during point measurement - a part of the triangulation process - in LPS):

As you can see, the radiometry is tough! This is why ImageEqualizer had to be used to perform radiometric corrections.

Most of the workflow was relatively standard (mission planning, data collection, and the photogrammetric processing), but some of the final product preparation steps were pretty interesting. Since one of the main goals of the entire exercise was to produce intelligence products that could be shared with other groups, special consideration had to be given to exactly how the data would be formatted for delivery to the other Empire Challenge groups ingesting the data. Since the groups accepting the data could have been using any number of software packages, the ERDAS/Leica team had to steer clear of proprietary formats. However, one thing that many image processing and photogrammetry products usually have in common is the ability to ingest images with an associated RPC (Rational Polynomial Coefficient) model. Here is a good description of RPCs in GeoTIFF. Since this was a military exercise, the images (processed as tiffs) had RPCs generated in IMAGINE and then were exported to NITF. This made is possible to pass along the final data products to several groups without any data format/interoperability issues. One thing to note is that "RPC Generation" was introduced in the IMAGINE 9.1 release in early 2007.

By the end of the project the total processing times for the various missions could be measured in hours. The basemap mission took the longest (about three days for the entire end-to-end process), but it had approximately 900 images along with the LIDAR data.

Here's a screenshot of an orthomosaic over terrain. The radiometry hasn't been fully processed in this image, but it gives you an idea of what the project area was like:

Triangulated Irregular Network (TIN) Formats and Terrain Processing

One issue in the mapping community is that there is no standard format for Triangulated Irregular Network (TIN) terrain files. Most geospatial applications use proprietary formats, which presents serious interchange problems when moving the data around (e.g. from clients to customers, or even within an organization). Unfortunately we are guilty of this as well in LPS, with our LTF TIN format. Many people get around the limitations of proprietary formats by using ASCII as a common interchange format, where the TIN mass points are listed in XYZ for each row (separated by commas, tabs, or whitespace). Some systems also support the notion of points codes for breaklines, which are a critical part of the TIN structure. The main problem with ASCII is that once you get over several million points, the file can be cumbersome to deal with - which means it may be necessary to divide up the data into tiles. Alternatively you can convert the TIN to a raster format, but this can be undesirable if you have dense mass or unevenly distributed points, or if you have breaklines in the TIN (since rasters don't support breaklines).

A case in point is the LIDAR data from the Washington State Geospatial Data Archive. While there are standards for LIDAR data, most commercial applications do not (yet) natively support it. Hence there is a need to make the data available in alternate formats. The data is available in ASCII and TIN format for each quarter quad, but the TIN format is in .e00 format, which is an old interchange format developed by ESRI. Hence, the site recommends Importing the .e00 files into ArcMap in order to use them. The only issue with that is that you need ArcMap... This is likely a reason for including XYZ ASCII as an option as well. Another option is a 3 meter DEM for the entire coverage area, which is possible to download from here. It is in Arc/Info binary grid format though...

So how do we handle all of this in LPS?

There are a few different options here, and the LPS and IMAGINE groups have been working on a solution. Prior to the LPS/IMAGINE 9.2 release, users had to either use the 3D Surface Tool in IMAGINE or the terrain Split and Merge tool in LPS Core. In 9.2, and moving forward in future releases, we are consolidating our efforts by extending the LPS Split and Merge tool and making it available in IMAGINE, which we have renamed to the "Terrain Prep Tool". It is available in Data Prep > Create Surface in IMAGINE, or from Tools > Terrain Prep Tool in the LPS Project Manager.
The Terrain Prep Tool adds new split/merge functionality inherited from LPS as well as resolving some longstanding limitations associated with the 3D Surface Tool (e.g. it dramatically increases the number of points that can be handled). For 9.2 we also added a few formats such as LAS and two flavors of ASCII (with and without point codes for breaklines). The 3D Surface Tool will likely remain available for a few more versions, until we have fully replaced it's functionality in the Terrain Prep Tool.