DIRSIG

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.

Oftentimes water can be a dominant signature in a polarimetric image dataset. Incorporation of water into a DIRSIG simulated polarimetric scene can be accomplished a few different ways, namely treating the water as (1) a volumetric medium having both surface and bulk medium optical properties or (2) a surface, reflecting only material described by a micro-facet based BRDF. This example has three boxes of water demonstrating the differences between the water medium material properties (with a flat and a wavy surface) and the microfacet surface water material. Note that treating water as a medium permits 1st surface reflection and transmission as well as bulk material radiative transfer, whereas the micro-facet BRDF water material only accounts for 1st surface reflected radiance effects. The water medium material utilizes well defined inherent optical properties of water that are contained within the DIRSIG model (validated here ) and is well suited for closed volumetric shape

We are pleased to announce the final release of DIRSIG 4.4.3.  This is a maintenance release primarily aimed are resolving bugs and addressing minor limitations: New reference documentation (installed with software) Fix to default GLIST and ODB rotation order Support for viewing exo-atmospheric objects with "Simple" and "Threshold" atmosphere models Improved support for defining spectral bandpasses in nanometers Improved speed when loading large ODB files Improved spotlight collection wizard New/Updated LIDAR demonstrations LidarBounces1 LidarDynamicGate1 New/Updated RADAR demonstrations SpotlightSar1 StripmapSar1 QuadPolSar1 One of the things we think users fill find most useful in this release is some new and improved documentation. You can find this documentation in $DIRSIG_HOME/docs (or via the Start menu item on Windows). A copy of this documentation is available here . Please browse the existing documentation and provide feedback or sugge

Terragen is a terrain modeling software package that has both a free version and a commercial version available for download. This program has a nice procedural engine for synthesizing realistic terrain relief in a matter of a few minutes. Within Terragen 2 Deep Edition, we created a simple fractal based terrain with a spatial extent of 10km x 10km and exported it to OBJ format via the "micro exporter" contained with the Render node. For the DIRSIG render, we simply created a mid-latitude summer (MODEL=2) and 23km aerosol model (IHAZE=1) MODTRAN based atmosphere and attributed the terrain with a 30% spectrally flat albedo. For a little sizzle, we also added a simple rectangular box and attributed with the fresnel optical property of water (n = 1.33, k=0.0). Additionally, it should be noted that we had to manually rotate the OBJ file (within Blender and re-saved to the same file) by 90 degrees since Terragen uses the +Y is up convention while DIRSIG uses the +z is up con

The new DIRSIG 4.4.2 release includes 10 new demos, bringing the total number of these feature focused simulations to 53. Some of these demos have been briefly discussed in other posts (for example, the expanded Geometry Primitives and Bayer Pattern Focal Plane demos). The following is a list of the new demos in the 4.4.2 release: Bayer pattern focal plane A set of example BRDF materials LIDAR returns from a sloped surface LIDAR returns from sub-pixel structures A geo-synchronous, exo-atmospheric "moon-like" satellite A 4-camera, division-of-aperture polarization system A 2x2 microgrid division-of-array (focal plane) polarization system An expanded set of primitive geometry objects An extended-area, directly viewable source An advanced UV mapping example Like the other demos included with DIRSIG, each demo is a self-contained simulation that can be easily downloaded (from within your local installation), unzip and run without any modifications. We consider t

The Final Release of DIRSIG 4.4.2 is out. This release is primarily a maintenance release to address a few bugs in the 4.4.1 release. The following is a summary of fixes and features added in this release: Significant performance improvements to LIDAR simulations (~20x faster) Adaptive sampling support in the Graphical User Interface (GUI) Data-drive focal plane support in the Graphical User Interface (GUI) Improvements to graphical "Simulation Preview" tool New extended-area, directly viewable sources New "Refinery" scene 10 new demonstrations Bug fixes related to using the "Classic" atmosphere model Improved compatibility with MODTRAN5 2.0.0 Issues with platforms on space based platforms Issues with platforms on the ground looking at exo-atmospheric objects Scene Editor upgrades New "General" tab with preview image Option for implicit scene "base directory" using the location of the .scene file More meta-data t