DIRSIG

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

It has been a pretty exciting year for the team at Spectral Sciences, Inc.  with the release of MODTRAN6 . This latest version marks a major milestone in the continued development of one of the most popular and trusted codes for simulating radiative transfer in the atmosphere. In addition to important science related advancements, this latest code also includes significant improvements to the general usability of the software. This includes a new graphical user interface (GUI) and the introduction of a formal application programmer interface (API), which let's codes like DIRSIG interact with MODTRAN in a far more robust way than previous versions allowed. New MODTRAN, new interfaces The major development in the interface area is a shift from the old "tape5" style inputs to a new JSON (JavaScript Object Notation) style input. In addition to improving the general readability of the input, the JSON document format is much easier to read in, modify and write back out. The

After a 5-year hiatus, we have decided to revive the DIRSIG blog in an effort to increase communication with the DIRSIG user community. We get a lot of emails asking the same questions and it would be a lot easier if we wrote up the answers to these questions and published them in an easy to find location. But the primary reason for that is that there is a lot going on these days and we want to tell everyone about it. Over the next few weeks and months our goal is to try and get everyone up to speed on important developments in DIRSIG land. Specifically, we will start getting everyone up to speed on DIRSIG5, which is the rewrite of DIRSIG4 that uses a new numerical radiometry approach and leverages multi-threading and multi-processing (compute clusters). We are also discuss our progress on GPU-acceleration of some key parts of the DIRSIG calculation (spoiler alert, it is incredibly difficult to migrate an entire code like DIRSIG to the GPU). It should also be noted that DIRSIG5 has

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