Using GTOPO30 DEM Data with CfsTmap
CfsTmap from Version 4.00.11 has the option to used GTOPO30 data either downloaded from the USGS site or from CDs that can be obtained via their site. GTOPO30 stands for Global TOPOgraphic 30 sec-arc Elevation data. This equates to about a 1km resolution (depending on Latitude) which works quite nicely with CfsTmap using the recommended scale of 4.
The DEM files used are very large. Downloads vary from 0.1meg to over 16meg depending on the area (empty areas of ocean compress very well!) but will expand to 56meg when unzipped so a CD-RW would be an advantage. The files required by CfsTmap are just the *.dem file and the *.gif file from any archive. These files must have their original filenames as that is used to evaluate the location of the data (they will be named W040n90.dem or something similar giving the Lat/Lon position of the top-left corner). Each DEM file covers an area of 40 degrees EW and 50 degrees NS so one file covers the whole of western europe.
The easiest way to explain how to use the DEM feature in CfsTmap is perhaps to go step by step through the creation of the Kauai Scenery.
Pick a location just to the North West of a box covering the limits of the Island ( N22*13.19 W159*15.8) and set
up CfsTmap with the coordinates.
Unlock all tiles and fill with grass (070707s1.bmp).
Select DEM->Import DEM Elevations (go into Elevations mode if you want to see the data but for the first layout these will all be zero as we haven`t reached land yet). The first time you use this function you will need to browse to the appropriate dem file (the dem GIF file will be displayed to let you see if you have selected the right DEM file for the current location). This is also the time to set, in the DEM requester, what type of Terrain you are making. For a project of this size (48 layouts) I would recommend using "Classlist" rather than TexRelief.. TexRelief will allow rotation so nicer coasts can be designed but the end files will be about 400k instead of 30k
Select DEM->Set Zero Elevations to Water. All the tiles will change to water on this first layout because of the shape of the Island)
Save this layout (hopefully using some sort of naming routine so you can keep track of which layout goes where - I used kau00,kau01......then for the next row kau10,kau11.....)
Use the 'E' button to step one layout left and repeat the unlock, fill, Import DEM, Set 0 to Water. This time you should see some tiles still grass. This is Land! Save this layout (kau01) and repeat again.
Once you have got to the end of the Island box (8 layouts in all) reload the first layout, step one layout south (the 'S' button) and repeat the whole process again (then back to the leftmost and step south again....you should require a total of 8 layouts across by 6 down.)
Because the actual spacing of data varies as you move NS (and rounding errors at various points) the elevations on the edges of one layout don`t always agree with its neighbours so the next stage is to reload the layouts, starting in the Top left, and using the Import ...edge Elevations in the Elevations menu to Import the West edge and North edge elevations from the appropriate layouts. You could also set the "Adjoining Layouts" for each layout at the same time.
Having done that you can go through and compile them all and take a look at your scenery. It will actually look quite good (except on the coasts!). Note that if you are using "Classlist" then you will need to create a classlist bgl covering the area - I used N20-N24 and W160-W156.
Now the hard work! Go through all the layouts that have coasts on them and start designing coastlines with suitable tiles. Work outwards where possible to get the "Coast" tile to be zero elevation on all 4 corners (to avoid the sea flowing uphill!). Lock them when you are happy then start work inland making the scenery look the way you want it.
It may seem a bit longwinded but I created the whole thing in about 4 hours. Obviously a lot more time could be spent in the final stage - I just relied on the matching routines and didn`t bother trying to place any Towns or Rural areas. It ended up mostly Grass and Woods.
UPDATE
Prior to the actual release of this version (but after creating Kauai) I have added a new function to the DEM menu. "Import W and N Elevations from adjoining layouts". This simplifies the matching up of Elevations. Now the procedure would be
Start with the NW Layout as before
As you step to create the next layout use the "Adjoining Layouts" button to set up the layouts touching on each side (even if you haven`t created the appropriate layouts yet - just type the name in)
Import the DEM data as before (including filling with land and so on)
Select the "Import W and N......." from the DEM menu
Save (and compile if you want)
Repeat with the next layout and the next until finished
I have chosen to Import N & W rather than all 4 sides because that would only work if you created all the layouts first (including importing elevations) then going back through all of them again to match the edges. It does mean that you need to start a multi-layout from the NW corner for it to work correctly.