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World Model Creation

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Marvin!:
Hi, I have just found Bridge Command and I am eager to create a world model.

I understand the requirements from the docs, but I need to know what software to use to create the world files.
I am presuming that SRTM data will be used. Can someone enlighten me about the actual proceedure of the creation of the variose BMP files needed.

Thanks,

Marvin.

forum_admin:
Hi Marvin,

Yes, one of the main sources of data for elevation maps is SRTM data, which can be downloaded from http://earthexplorer.usgs.gov/. In addition, for the USA, the NGDC Coastal Relief Model (http://ngdc.noaa.gov/mgg/coastal/startcrm.htm) is a very good data set which combines land elevation with sub-sea bathymetry for the US continental shelf.

Since I have last worked with these data sets, the data formats available have changed, so I need to investigate further what tools are available to convert the data into BMP format, suitable to load into Bridge Command. I will look into this over the weekend and post an update here.

In the UK, the Ordnance Survey have recently released a reasonably high resolution digital elevation map (Land-Form PANORAMA on https://www.ordnancesurvey.co.uk/opendatadownload/products.html) under their OpenData licence. However, this is referenced to the UK National Grid, so I am currently looking at how to re-process this into a latitude/longitude format using WGS84, the standard datum used by modern charts and gps.

Once you have your heightmap in an image format, you can also generate a texture image to display on the terrain when it is loaded in the program, which should be the same image size as the heightmap. For this I currently use L3DT (http://www.bundysoft.com/L3DT/).

The radar image file is now only used as a map in the scenario editor and map controller, as the radar image is simulated directly from the terrain. Therefore I normally use the same image as the land texture.

I will report back on tools to convert the available datasets into a bitmap image,

James Packer

forum_admin:
To follow up:

The best data source for importing STRM data for terrain models appears to be CGIAR, who maintain an SRTM dataset with voids filled in (http://srtm.csi.cgiar.org).

I have also put together a tool to convert this data from ArcInfo ASCII format into an image format suitable to generate a heightmap for Bridge Command. This creates a 'pgm' file, which can be read in a good image editor, such as the free GIMP (http://www.gimp.org/downloads/), and saved as a .bmp or jpeg file.

To use this data to generate a height map image:
>Go to: http://srtm.csi.cgiar.org/SELECTION/inputCoord.asp and select the area you want.
>Select 'ArcInfo ASCII' as the file format
>Search and download the data you want

>Download the conversion tool from http://www.bridgecommand.co.uk/file/import.exe
>Save import.exe somewhere
>Drag and drop the .asc file you have downloaded with your data onto the import.exe program file
>Set the sea depth when requested (SRTM has no sub-sea data)
>The program will process the file, which will take a number of minutes, and may appear to freeze while writing the output file
>When done, the output file will be saved in the same location as the input, with .pgm appended to the filename. Note the TerrainMaxHeight and SeaMaxDepth values to use.
>Open the .pgm file in your image editor, and follow the documentation to save this in the correct size as a .bmp or .jpg file.

Please note the terms of use of the CGIAR data at http://srtm.csi.cgiar.org/SELECTION/SRT_disclaimer.htm.

Please let me know if this is helpful, or if you come across any issues,

James Packer

Marvin!:
Meny thanks, James.
That is a great help!!

I will let you know how I get on.


Marvin.

ignacio70:


"Once you have your heightmap in an image format, you can also generate a texture image to display on the terrain when it is loaded in the program, which should be the same image size as the heightmap. For this I currently use L3DT (http://www.bundysoft.com/L3DT/). "

Hello Might you explain how the program L3TD is used to generate the field, I fail to understand how to use it from the map image. i have a image in BMP or JPG downloaded and i have the importe.exe image.

Thanks

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