A recent paper on using DIRSIG to model the next generation Landsat

A paper we submitted to the Remote Sensing journal was just published in a special issue titled Thermal Remote Sensing Applications: Present Status and Future Possibilities. The title of the paper is Simulation of Image Performance Characteristics of the Landsat Data Continuity Mission (LDCM) Thermal Infrared Sensor (TIRS) and it outlines how we have been working with NASA and USGS to model Level-0 style data products to evaluate system performance including image registration, MTF, jitter, etc. for the next generation Landsat satellite (what will be referred to as "Landsat 8" when it is launched in early 2013). The article also explores how some proposed on-orbit calibration procedures might perform by modeling the data that could be collected using the detailed system description that has been constructed with NASA and the payload contractors over the past two years.

The paper is currently "open access" and free to download.

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LIDAR Point Cloud Visualization

A common question we get asked is how to visualize the point cloud data produced by either the Linear-mode or Geiger-mode LIDAR simulations. First, you should remember that the point cloud files produced by the "APD Processor" are simple ASCII/text files. Each line is the entry for a single return or "point" in the point cloud, including the point location and some attributes that vary depending on whether you modeled a Linear-mode or Geiger-mode system. For a Linear-mode system, a point cloud file will generally look like the example below: 12.7388 -45.3612 -0.0256 5.0290 0 0 0 0 12.8169 -45.3612 -0.0264 4.8362 0 1 0 0 12.8950 -45.3612 -0.0271 4.8362 0 2 0 0 ... 32.4008 -25.5446 10.5945 4.6783 0 65533 0 0 32.4781 -25.5446 10.5953 5.8959 0 65534 0 0 32.5360 -25.5640 12.5408 5.9185 0 65535 0 0 The first three columns are the X/Y/Z location of the point return. The 4th column is the intensity (in photons). Since Linear mode can support multiple returns per pulse, t...

Viewing and Importing DIRSIG Output Images

We are often asked what programs can view DIRSIG's image outputs and how to import the raw DIRSIG image data files into other tools for further processing. For basic image viewing, DIRSIG-4.4.0 now includes a very simple viewing tool. Launch it from the main simulation editor window by selecting the "Start image viewer" option from the "Tools" menu. If you run your simulation from the GUI simulation editor, new image files are automatically added to the list in the image viewer as they are generated. If you want to manually add files to the list, simply select the "Open" item from the "File" menu or the toolbar. Here is a screenshot of the main image viewer window. The top part contains the list of currently opened files and the bands within those image files. To view a single band as a gray-scale image, choose "Single Band Display" from the combo box and then click on the image band that you want. Finally, click "Load Band...

DIRSIG5: An introduction, a timeline and a paper

Although we will be devoting more time to this topic in the blog, many of you are aware that the next generation version of DIRSIG (aka DIRSIG5) has been under development for the past 2 years. This was a ground-up, restart from zero, etc. effort that establishes the DIRSIG modeling toolkit for the next decade. New core, new approach Although we have developed a compatibility layer to allow existing DIRSIG4 simulations to run, the DIRSIG5 model is radically different under the hood. The lightweight and highly optimized radiometry core uses a different numerical radiometry (light transport) approach than we used in DIRSIG4. In addition to being faster (less work to get an accurate answer) this algorithm is far better suited for parallelization. As a result, we have implemented micro-scale parallelization (multi-threading on multi-core CPUs) from the start and work on macro-scale parallelization (MPI distribution on cluster-style computing) is getting underway. This radiometry core al...

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