Celestia Forums

I want to use a very huge 440 mb satellite foto as virtual texture. The resolution is 5 m2 per pixel, there are 4 parts with height 8728 width 8404 pixels each.
The picture's left upper coordinates are Gauss Kr??ger M31 403948.0 5260411.0, spacing of pixels is 5 m.
It shows an area of about 70 km2 in the Austrian Alps, Salzburg and K?¤rnten in high detail.

Can anybody give me some advice how to calculate lon/lat from Gauss Kr??ger and how to split the picture in textures to be used in Celestia VT ?

Any help is highly appreciated.

HLOQ

hi HLOQ,first you should check if the map you want to use is in Equirectangular or UTM projection,probably UTM,so you will need to reproject it to Equirectangular for it to be accurate in Celestia.Jestr

Google gives you (for example) the following info links:

Gau??-Kr??ger-Koordinatensystem - Wikipedia
Frank Swiaczny: Gauss-Kr??ger Koordinaten
Koordinatentransformation UTM nach Gau??-Kr??ger
Kartengitter: Swissgrid, Gauss-Kr??ger, German Grid, UTM

You should note, in case you are reprojecting, that Gauss-Kr??ger(German Grid) and UTM are two slighly different projections. The first uses the 'Bessel-Ellipsoid' whereas the second uses the 'WGS84-Ellipsoid'. Also note that official Austrian map material uses a slightly moved 'Bessel-Ellipsoid'.

In case you've finally understand and processed all this coordinate-transformation and reprojection stuff, you can start teaching us all

maxim

thank you Maxim and Jestr

the picture is "orthorectified" and "norded in" - I guess that means the same as equirectangular, so I don't have to reproject (which would be beyond my intentions
a small part of it has been used for a virtual flight / 3d hiking map application together with a 25m-grid DEM, that fits very accurately (http://www.coolmaps.at/rennweg.html)

now it seems to turn out to the question how to get lon/lat for the 4 corners, given Gauss-Kr??ger coordinate for NW and pixel spacing, height and width for NE,SE,SW, I could not figure out from Maxims links how to calculate that

and then how to cut it in how many pieces/levels ...

hloq

Please read http://www.lns.cornell.edu/~seb/celestia/textures.html#2.5

it includes links to other VT documentation and to VT creation utilities.