Problem importing Whistler satellite imagery into Terragen: Archer tutorial

Started by davidcowell, January 11, 2012, 07:49:28 AM

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davidcowell

Hi,

I've just started having a look at Terragen 2 for a 3D mapping project, so please forgive my general ignorance in advance!

I came across a very useful tutorial by Ryan Archer which seems to do exactly what I'm looking for (http://www.archer-designs.com/tutorials/terragen2/working-with-gis-data/).

Everything was going great until I got to importing the satellite imagery into Terragen. It looks OK, but when I render the image it's obvious that the projections don't quite match (imagery of the sea is draped over hills in places - see attached file). I followed all of the instructions (centering both layers, using a Y projection, setting the square size correctly). I also noticed that if I look carefully the imported image does not quite fit the imported heightfield overlay in the small view at the top left when I toggle between them, and that the image isn't perfectly square (the heightfield is).

I'm guessing that the problem might be related to the projection of the imported files, or possibly the file types themselves. I'm using a trial version of GlobalMapper to do the export, and both files are UTM with Datum NAD83, which is what they automatically load as, though I noticed that the satellite image file loads with a message saying "the projection/datum of this GeoTIFF file could not be determined automatically", before appearing to do it correctly. When loaded in GlobalMapper they align perfectly.

Is there a specific file type, or anything else you need to do in GlobalMapper when exporting the image file? I've tried using JPGs and BMPs, but with the same result.

Any ideas or suggestions would be very greatly appreciated!
Thanks,
Dave




Aerometrex

Hi David,

I'm also using real geospatial data to generate fly-through with Terragen 2 and I actually don't bother to use the geographic info as I'm using only one heightfield/image pair.

In Global mapper I first export my DEM as a TER format.
I make sure that when I export my image in GeoTIFF I use the option "Reset to Last Exported Bounds" in the GeoTIFF Export Options> Export Options.


I first load my heightfield and use the option "Auto georeference from file"
I copy the XY coordinates for the Statistics section at the bottom.

I load my Image map shader.
I past the XY coordinate under Size. I make sure Projection type is Plan Y.

All done.

Check out some of my latest work with digital aerial imagery draped over a dem here: http://www.youtube.com/user/Aerometrex/videos

I am passionate  about the art and science of digital aerial mapping, photogrammetry, geospatial information, VR and 3D modelling.
http://aero3dpro.com

Oshyan

The main thing you need to ensure is that they are in the same project and are the same size and aspect ratio, or at the least share a common edge or center point which you can use to align them. You could try TIFF format for export as well.

- Oshyan

davidcowell

Thanks for the replies.

Particularly to whoever responded from Aerometrex. I followed the instructions exactly, despite being sure that I had done all of the same things before, and this time it worked fine!

I was also very impressed by and interested in the fly-throughs on the website - I wonder if it might be possible to contact you directly to discuss what you do, and potentially the project that I'm engaged on? If so, give me your name, and I can contact you through the Aerometrex website.

Many thanks again,
Dave