General Question Converting LROC images to orbiters elevation and surface files

kalral

New member
Joined
Nov 22, 2020
Messages
9
Reaction score
6
Points
3
Location
Germany
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.
 

4throck

Enthusiast !
Joined
Jun 19, 2008
Messages
3,047
Reaction score
203
Points
88
Location
Lisbon
Website
orbiterspaceport.blogspot.com
You can try "Terrain Toolbox" to export/import surface tiles. Unfortunately it doesn't work with the latest D3D9 clients.

 

kalral

New member
Joined
Nov 22, 2020
Messages
9
Reaction score
6
Points
3
Location
Germany
@4throck Thank you for the reply. That is sad to hear. Lets see if the addon owner can release the source code so that I can fix it up else I will try to write a python version by following the PlanetTextures.pdf or I can also go through the code here.
 

ggalfi

New member
Joined
May 31, 2020
Messages
20
Reaction score
13
Points
3
Location
Budapest
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).
 

kalral

New member
Joined
Nov 22, 2020
Messages
9
Reaction score
6
Points
3
Location
Germany
@ggalfi Thank you very much for the detailed answer. I read the problem of syncing down in the ground in the Apollo 11 thread posted by you. That is sad to hear but I guess upto level 17 I shouldn't have any problem with the physics in Orbiter. I am just experimenting here as Orbiter is already an excellent and accurate simulator and I am just trying out various possibilities of including image processing into it so that I can learn how Nasa is doing this.

I am also going through the code here which you guys might find interesting. It is not that developed like Orbiter but it has some other things going which I find very interesting to learn about the dynamics side of things. The author of the library, a professor in University of Colorado Boulder said that they used the same code in Emirates Mars Mission. It also has got a nice model of it in the code.

Very excited to listen that you will post your implementation online. Will learn a lot from it and also exited for the Apollo landing sites. Its an enormous undertaking. Hope I can be of some assistance to you.
 
Top