Author Topic: Gtopo30 Mapmaking with satelite data (Read 417 times)

Schutt · « **on:** January 07, 2005, 03:58:28 AM »

Hi all,

I am trying to build a map of a terrain in northern europe,
Norway around Bergen to shetland isles.

I tried to use the gtopo30 database to get a bitmap of elevations and then convert this to AH2 terrain data with bmp2map.

While doing this i encounterd various problems. Did anyone make a map from elevation data, how did you do it and what is the best source to get the data?

Gtopo30 delivers a coulerd bitmap that has to be converted to greyscale for bmp2map. I got this part working sometimes, but most times i end up with a water picture with some verry high pieces, i think i just do something wrong. Working with photoshop 6, anyone who could explain how to do it correct?
The bitmaps deliverd have a point for every 0.5degree of angle on latitude and longitude. Now the picture/terrain that comes out is angle true, that means when i fly at course 030 i come out where i should. BUT the distances are to long, the further north the worse. So for a historic mission from england to bergen it is to far. Anyone know how to stretch the terrain correctly to get correct distances, or which program to use?
On the terrain site there is another program, called mapmaker, that promises to make ah2 terrains from gropo30 maps, but i couldnt get that to work. Anyone used it? does it contract the map or do i have the distance problem again?
Anyone know where to get more detailed terrain info in computer format, the problem is with gtopo some fjords shrink to non existence, i would like to stretch the terrain with the fjord for another project, but its not there so nothing to stretch.
Is it possible to place manned aa guns in the countryside, maybe putting an airfield a bit away to man them but have them not on the airfield?
Any norway maps made yet? Which part of norway? i am intrested in the north cape and around bergen.
I am a programmer myself, i thought about converting bmp to ah2 terrain myself. Is any information available on the terrain data in ah2, thats the *.typ and *.elv data files i think?

ciao and happy building to all of you!!
See ya all and happy building !!

NHawk · « **Reply #1 on:** January 07, 2005, 05:14:19 AM »

Quite simply you're using the wrong GTPO web site. Greyscale data is available at..

http://edcdaac.usgs.gov/gtopo30/gtopo30.asp

Most if not all of your problems will vanish if you use this data. Including the inability to us mapmaker.

FalconSS · « **Reply #2 on:** January 07, 2005, 06:11:37 AM »

Sounds like the mapmaker program would be more suited for your needs. I have the program and all the DEM files that go w/it covers the whole globe, let me know if you're interested I can walk you through it.

Schutt · « **Reply #3 on:** January 07, 2005, 07:48:42 AM »

Ahh thank you for the quick anwser.

I checked the site you said.. downloaded the europe tile, now i have the DEM data and a bitmap, but the bitmap is to bad resolution to use as elevation and i dont know how to open the DEM data.

I think i have to use mapmaker with these dem files then?

Eplanation of where i get mapmaker how i install and use it would be nice then.

ciao schutt

NHawk · « **Reply #4 on:** January 07, 2005, 10:28:38 AM »

Mapmaker is available from ah-terrains. To install, just unzip it into any folder you like.

You will also need this file for mapmaker.

Global USGS Ground Cover Data Set

Copy that file and the DEM files you have for Europe to the same folder you unzipped mapmaker into.

Start mapmaker and click on 'input parameters. Enter the longitude, latitude and width in degrees for the area you want. Then click 'Load Data'. Once you have the area you want in the display area, click 'Export Data'. You'll find a mapmaker.elv and mapmaker.typ file in the folder. Rename them to the same name as your map and move them into your map's folder. Make sure you've already created a blank map in the terrain editor so you have somewhere to move those files to.

MachNix · « **Reply #5 on:** January 07, 2005, 01:02:51 PM »

Schutt

On your manned aa guns in the countryside question, I believe you can.

On converting elevation files to ah2 terrains, this is what I know:

The *.typ files are 512x512 and contain the tile numbers – 8-byte integers 0 thru 6 – that are for the blue "+" signs in the Terrain Editor. The file begins (file address 0) at the lower left and runs left to right. The final point (file address 3FFFF) is in the upper right corner.

The *.elv files are 2048 wide by 1024 high. Actually they are set of 1024x1024 16-byte integers that contain the elevation data for each blue and green "+" sign. The file starts (file address 0) with the blue "+" in the lower left corner of the terrain, moves to the right alternating between the blue and green "+" signs, and finishes with a green "+" on the right. The next row is all green. The row after that again alternates between blue and green. Therefore, the terrain's top and right edges consist of all green "+" signs. The file ends (address 1FFFFF) with the green "+" in the upper right corner.

Hope that is clear enough to help.

MachNix

Schutt · « **Reply #6 on:** January 07, 2005, 03:19:33 PM »

Ahhh yes that will help.

Got mapmaker to work thank you all. Mapmaker makes me great maps, but the ability to change the bmps in photoshop was a nice too.

For now mapmaker works great, with my special problem in norway its a bit tricky because the fjords are to small so they get leveld up in the maps. Will put that problem away for a bit.

The fileformat will help me... ill work on it.

ciao schutt