Georeferenced data test

[bigben]

Hi All

I've had a couple of questions about the methods I used for these images: http://www.planetside.co.uk/forums/index.php/topic,18550.0.html so I thought I'd make some notes here for reference.

First off, I'm preparing my data in GlobalMapper which, among other things, lets me mix data of various resolutions and from various sources.  I've found this to be a better way to mix data rather than loading DEMs from different sources in TG.  I used to export TIFFs but I'm now trying out goetiff.   For example, my global terrain of the earth includes ASTER DEM with bathymetry on top of which I add SRTM4 or USGS 10m NED.  For texture maps, I load in an image from the Blue Marble series.

TIPS:
* Load ALL of the data you're going to combine before exporting files. GIS applications will use the highest resolution data available to fill holes, which TG doesn't do. Using geotiffs from different sources in TG may produce noticeable effects at the edges.
* Centre the lat/long projection at 0,0. It's not critical but it makes working with full globe data/images easier.

Once I've got all of the data and imagery loaded it's pretty easy to export different areas at different resolutions. High resolution for the area I'm looking to render and then a wider area at lower resolution for distant terrain and upwards to a complete global terrain/texture if required. Then it's just a case of loading the terrain/images into TG from lowest to highest resolution.

For planetary renders this makes for a relatively simple TG project
[attach=1]

For Mars, it's possible to load the entire 128px/° DEM at once. (I've split them into 2 geotiffs) and a 0.025°/px texture for just under 6Gb RAM usage. This DEM has a 2° hole at the poles so I've filled these with the 64px/° DEM.
[attach=2]

For renders near the surface it pays to change the coordinates for the apex of the planet to the area you want to render.

[Dune]

Thanks, Ben. I copied this to my tutorial section, hoping to use it some day.

[bigben]

Making some progress with data for Mars after sorting a few technical issues out (images inconsistently loading with the wrong projection in GlobalMapper).  The gaps in the range of resolution is proving challenging but it's also forced me to rethink how I export the data which should be quite useful for mapping out terrains for animations.  Here are some samples of the terrain data with fractal detail disabled.

MOLA128. the original
[attach=1]

HRSC plus one strip of HIRISE
[attach=2]

And yes, we're gonna need a mask    This one's just a quick geotiff edited in Photoshop but as geotiff needs to be RGB for this to work the extra effort of positioning a SSS will be worth it.
[attach=3]

The HIRISE data here was exported at 38m/px, a long way from its full resolution of 1.9m for this one, but good enough from this distance.  Given the noise from the photogrammetry processing I probably wouldn't try higher than 5m, but we shall see.

[Oshyan]

Man that HIRISE data is amazing-looking. I really hope this ends up working out, I've been looking forward to a higher resolution real Mars animation for a long time!

- Oshyan

[bigben]

It certainly is.  This is 2m resolution at a camera height of 50m. No fractal detail, render detail = 1.  It won't be without its challenges but I'm quite hopeful. Lots of data to explore.

[Tangled-Universe]

Stupendous, you can even see the erosion channels 

[Oshyan]

Very nice indeed. The banding is a bit of a concern, but the detail is undeniable still. Check out this video, also using HIRISE data, but apparently with even more detailed data (perhaps the data just in Candor Chasma is better?): https://www.youtube.com/watch?v=0WsjeJiAR4E
No major banding either...


Edit: this one is pretty incredible as well: https://www.youtube.com/watch?v=QutMf79sFhk
Or check out the crazy detail in the rocky talus slopes in this crater! https://www.youtube.com/watch?v=ftS4rujxJWo

- Oshyan

[bobbystahr]

WOW..that mars explorer does pretty nice animation on all 3 of those...are the over hangs real do y think, or just an optional delusion....?

[bigben]

Don't forget I'm rendering without fractal noise to see what the data is really like. This one is at a camera height of 1.5m. Foreground is 5m resolution, 2m res starts about 1/2 way from the bottom.  Need to change flow factor to something really low or remove it altogether as it does odd stuff with the small mounds resulting from noise

[bigben]

WOW..that mars explorer does pretty nice animation on all 3 of those...are the over hangs real do y think, or just an optional delusion....?

From a  data perspective I'd say they're an optical illusion. The typical data processing for those images to get the terrain would create a heightfield rather than an arbitrary mesh so there would be no overhangs.  The imagery has a much higher resolution than the terrain which helps make it look so good.  I'm still getting used to the scale of things on Mars, but some of those "ground level" animations I would guess are at a camera height of at least 50m and probably more like 150-300m. The crater wall in my image for example is 3km away, but even noisy 2m data at that distance looks pretty great

[bobbystahr]

Don't forget I'm rendering without fractal noise to see what the data is really like. This one is at a camera height of 1.5m. Foreground is 5m resolution, 2m res starts about 1/2 way from the bottom.  Need to change flow factor to something really low or remove it altogether as it does odd stuff with the small mounds resulting from noise

that's pretty amazing...having a great time exploring your Grande Canyon btw

[bigben]

that's pretty amazing...having a great time exploring your Grande Canyon btw

Pretty easy spend many hours exploring that. Enjoy  The other good thing about using geotiffs is that you can chop and change your elevation data to be more efficient for the area you're working on without having to adjust too much.  Those geotiffs are pretty big but you don't need 10m data for everything in a scene and it's possible to create multiple TIFFs at increasing dimensions and lower resolution to get a very expansive view for 40-80mb of LZW compressed geotiffs, leaving more RAM for plants etc...

[bobbystahr]

) The other good thing about using geotiffs is that you can chop and change your elevation data to be more efficient for the area you're working on without having to adjust too much.  Those geotiffs are pretty big but you don't need 10m data for everything in a scene and it's possible to create multiple TIFFs at increasing dimensions and lower resolution to get a very expansive view for 40-80mb of LZW compressed geotiffs, leaving more RAM for plants etc...

You should really publish a complete method of how you do what you do as a single volume .pdf so even a raw noobie could take advantage of this powerful feature TG has that none of the others use. It's tho only spherical world which is why it works so well I'm guessing.
I guess one could collect all the posts and order them and I would have when I was 40 but at 65.5 yrs old I'm more content with making the resulting pics.

[bigben]

You should really publish a complete method of how you do what you do as a single volume .pdf so even a raw noobie could take advantage of this powerful feature TG has that none of the others use. It's tho only spherical world which is why it works so well I'm guessing.
I guess one could collect all the posts and order them and I would have when I was 40 but at 65.5 yrs old I'm more content with making the resulting pics.

I'll try and make up a tutorial once I figure out what works and what doesn't but that requires others to have (access to) the data and a GIS application.

Of more interest to you will be that I'm going to be making a more RAM-friendly version of the Grand Canyon datafiles.  This was just a quick release so that people can play with it now. Producing the data is a lot easier than the previous methods I had for creating tiled terrains so I may make a number of TG-friendly datasets available for people to use

[bobbystahr]

Of more interest to you will be that I'm going to be making a more RAM-friendly version of the Grand Canyon datafiles.  This was just a quick release so that people can play with it now. Producing the data is a lot easier than the previous methods I had for creating tiled terrains so I may make a number of TG-friendly datasets available for people to use

have I said woo hoo lately.....should be awesome Ben