Digitising A Railway

Using the digitiser to create a layout.

This tutorial discusses using the Rail3D digitiser to create a layout of a prototpe railway - it will use the real-world features of the digitiser to calibrate the layout to lat/lon coords and download dem elevation data.

Step One - Preparing the maps

Preparing maps for the digitiser has been discussed elsewhere, in this example I am going to use a set of tiled maps prepared for a gps program.

The gps program I use is gpstuner from megalith systems - unfortunately the basic version has now been replaced by a new product called gps Atlas. gpstuner can accept maps in various formats, but they all require a .gmi calibration file: the digitiser can now read these gmi files and use map sets prepared for gpstuner. Fortunately, you don’t need gpstuner to prepare the maps you can do it by writing the gmi file yourself (it’s ascii and the format is fairly obvious). Even simpler, you can download the map preparation program (Map Calibrator) from http://www.filehippo.com/download_mapcalibrator and use that to prepare the maps.

So, if you have not already done so, download the map calibrator and use it to create a map set for your new layout.

1. Create a folder to hold the map set for the layout.

2. Run the Map Calibrator:

3.Zoom into the area of interest (click the Globe icon to reload the map):

4.Once you have found the right area of the map (and zoomed in/out to an appropriate level of detail), Click the save icon and select “Save Map” - save the map to an appropriate location and name. Note also that the map calibrator also creates the required .gmi calibration file:

5. Repeat with as many map sections as necessary to cover the railway you intend to create:

Step Two: Create an xml digitiser session.

The digitiser can use the maps created above if it has an xml digitiser file.

The xml file must specify the folder the maps are in, and the latitude and longitude limits of the layout in this format:

 

	F:\Oberammergaubahn
	47.35371061951363
	48.228332127214934
	10.5029296875
	11.8927001953125

This tells the digitiser where to find the maps, and the layout extents - the map calibration files (.gmi) caibrate the individual map positions.

You can download this set of maps and the xml digitiser file from http://www.rail3d.info/example/oberammergaubahn%20maps.zip

Step Three: Open the digitiser

Start Rail3D and open the digitiser. (Tools menu “Digitising Wizard”)
In the digitiser “File” menu, click “Load Session”
In the “open Session” dialog, change “Files of Type” to “xml Sessions”, browse to the xml file and open the xml file

The digitiser should now read the xml file and (provided the file paths are correct) open the referenced bitmaps.

You are now ready to start digitising the layout. I prefer to import the terrain first, and lay track on top of the terrain (this helps to get the elevations approximatly right to start with). Alternatly you may prefer to put the tracks in first and set the elevations by hand.

Step Four: Importing dem terrain.

You may need to scroll the digitiser to find the maps tip: As soon as possible, enter at least one place marker (using the digitiser ‘T’ tool) - this helps to locate things especially if you have a big map area.

Click the dem button on the digitiser:

and mark the area you want to import terrain for by clicking on the map:

Click the Commit button (!) to import the terrain, the terrain import dialog appears:

Note: The Rail3D digitiser can download dem elevation data from the internet and use it to create terrain surfaces. dem data is stored in a sub-folder of the Rail3D folder called “dem” - if this folder does not exist the digitiser will create it.

If the correct dem data file is already present in the dem folder, the file name will appear in the “Browse” box (as in the above picture). If the dem file is not present, the box will be blank

See SRTM- The Hard Way and UsingSRTM Terrain Data for more information on dem elevation data

If the dialog shows the dem file (as above) go straight to the import step below. if the filename is missing you will need to locate the right dem section:

Manually: Visit the CGIAR site, download the correct file, unpack the dem tiff file and use the browse button to point the digitser to the file.
Automatically: Click the “Download” button - the digitiser will download the correct section form the cgiar server and unpack the tiff file into the dem folder. This may take some time (it’s a big file).

Importing dem data

For this initial terrain import, select 25% (360m), this will give the general shape of the terrain over a large area - you can import more detail where required later if necessary.

Click the Import button to import the terrain:

The terrain is imported into the marked area, if you click the terrain points button in the digitiser, you will see the imported points:

Complete the terrain import for other areas of the map as required and save the layout.

Note. if your layout crosses the boundary between two dem data sections, you will only get data from the currently selected segment. Rail3D selects the most likely segment. You will need to change the filename to the other segment (And probagbly download it manually) to import the rest of the terrain data.

Press the triangulation button (in Rail3D) to triangulate the imported points and generate the terrain mesh. Save the layout.

Step Four: Laying Track.

We can now use the digitiser to lay track.

Click the “Track digitiser” tool and click along the route of the railway in the map to digitse the railway:

Notes:

Set the track laying options before you commit the track
If you have already imported the terrain, ticking “Lay track at terrain elevation” will lay the track at approx the right elevation.
You can create roads in the same way.