Hi,
I am trying to create some high resolution surface elevation and texture files for the moon surface to investigate whether it is possible to include OpenCV into orbiter to do some image processing. Right now, I have got some high resolution elevation files of Apollo 11 and 12 landing sceneries
here but I don't have any clue as to how to achieve the same result with other images. Is there a method or a tool that I can use to do that? If any one has a step by step procedure to follow I would be grateful.
Thanks.
The process has multiple steps and slightly differing for surface textures and elevation. For textures the procedure is the following:
1. Download some raw NAC images which you cover the area you are interested in. I prefer to use here overhead (lunar noon) lighting conditions but you can select any other type here. I don't like these sunrise-sunset images with long shadows because, despite they are spectacular, however as textures they work well only at very specific lunar phases.
2. With the help of USGS ISIS toolkit you can create a mosaic from these pictures which are already georeferenced (so for each pixel you can determine the lat-long coords). Technically you will get a GeoTIFF file as end product. It is even possible to download some out-of-the-box GeoTIFF-s for the landing sites, however they are usually taken at sunrise-sunset which is usually not my choice.
3. To avoid decal effect I've fitted (on large scale) the GeoTIFF pixel intensities to the original Orbitersim textures.
4. From the fitted GeoTIFF I create the surface tiles for Orbitesim with prefered LODs.
For step 3-4. I used my "swiss army knife" toolkit which I developed solely for this LROC -> Orbiter transformations. It is a command line application written in Java, and I plan to share it as an open source stuff, but I have to consolidate it for publication (e.g. to write some doc), though this is not on the top of my TODO list.
For elevation the path is a little bit different:
1. There are more or less suitable Digital Terrain Models (DTMs) for all the Apollo sites out there(and maybe for some others), so I've never built elevation map on my own. You usually get therse DTMs as GeoTIFFs.
2. There is again some need to fit the DTM to the original low-LOD tiles. The reason here is a bit different than for the surface textures: I cannot force the Orbitersim physics engine to use the higher LOD elevation in the calculation,s which results in sinking and floating objects. To avoid this problem, I have tried two different methods. essentially both of them move the high LOD elevation closer to the original elevation map at least in the vicinity (<100m) of the landing spot.
3. Then you create elevation tiles from this GeoTIFF, I again used my own toolkit to do so.
There is 0th step here which I've just begin to experiment with, is to build the DTMs on my own. I want to do because the currently available DTMs are covering a fairly large area (few tens of square km's), which is good, but that smoothes out smaller (few meters in diameter) craters, which is not so good. So I'd like to try to build smaller DTMs of the neighbourhood of the landing site with finer details. For that task there is the Ames Stereo Pipeline , also available as open source.
I'm currently working on further Apollo sites, in historical order and if no new issues will arise, you may expect them in the upcoming months (Apollo 14 LS is almost ready).