Hi Bill I have detailed all the steps.
Its just a case of clicking on buttons as very little else you need do, except lay depths as required and open up rivers, or attempt to, as required. Estuaries and wide rivers are usually already opened up.
I use srtm2 but havn't looked at USA file.
The files are in srtm2 and are hgt files.
Perhaps do a test download on one of these.
Download a few relevant files but make sure they are next to each other.
Bottom left hand corner if the map is the file coordinates.
The files for my area are, as an example, N52W003/4/5 and N53W003/4/5 (6 files at about 60 miles square each)
Store them anywhere. I have downloaded quite a few and building up a collection so have them in the srtm2 folder.
3dem will open other file types but hgt files are the ones I use.
I will make the scenery at the same time as I write it.
Make a seperate folder for each scenery you make, and put the scenery files in it.
1. Open 3dem first which is blank when opened.
2. File/Load terrain model/srtm data/ hgt-bil. click OK.
3. Open your srtm folder you made. Holding down control and select say 6 files next to each other which you have downloaded. (JUST AN EXAMPLE) . Have opened up to 8 at the same time but you may only need only2. Also if opening too many you may run out of computer memeory. They automatically join correctly if ajacent to each other.
4. So that loads a large area of about 150 miles square and it shows the sea as blue. For your area if no sea is showing blue....
5. Colour Scale/Modify Scale/ Islands-Ocean, with a 0 in the Sea Level Box, (important for later when making no data zero).
6. Operation/Patch Missing Data. Draw a box around the whole map. Press enter and this fills any missing voids. Or forget this part.
7. Operation/Select Smaller Area. Draw a box around the required area with mouse and press Enter.
They don't have to be in this order but just to explain make the area selected larger than what you actually want as we have to change the file type and you lose a bit of the map
8. Operation/Change projection/Convert to UTM Projection. tick WGS84 in the panel that opens but probably already ticked and OK it.
9 You can now crop it more to size, etc as previous, but still leave it a tiny bit larger than required for a final file change later.
10 Save map as USGS ACII DEM and give it a name
That finishes the 3DEM part.
11 Open the Scenery Designer then VT Builder. If you don't have VT Builder can email a copy.
Also when you finish with it it may still be open and you may not be able to open another another program. I closed it with windows task manager. Crl Alt Del
12. Layer/Import Data/Elevation and open the 3 dem file you saved.
13. Map opens, then Export Area/Set to extants.
14. Then "Elevation and Export Elevation". Give it a name and save.
15. Merge and Resample Box opens, Size at that Density with 2 values for X and Y sides of the map, First is X, 2nd is Y.
16. click "any size" in box below and in the box that is the longeSt size of the map. X or Y as sown in sample box, put 2048 (this is the largest size to get the best resolution).
17. So the smaller side is the fraction of the figures in to box, say 680/694 or whatever figures given, times 2048.
18. Click OK and map is made. I think it should be in the same folder as you saved the 3DEM file.
Open the Stentec Dem Editor and open the .bt file you just made and thats the greyscale terrain made, complete with co-ordinates.
Didn't open for me so pressed control Alt and Del on keyboard to close down vt.builder.
19. We need to clear the sea which is at the 0 figure we set at the beginning. so Dem/Set no Data/Single height with 0 in box.
This makes the sea as a pink dem and then lay some depths as minus values in metres.
The more the better as generates the map quicker in scenery designer.
Then interpolate to create the final grey-scale map which now includes the depths you laid.
20. Just one more little step to get it ready to be generated in the scenery Designer.
Before saving with a name-- Dem/Convert Projection/Scene .. with wgs 1984 in box. This rotates the map a fraction.
Earlier I mentioned make the map a tiny bit bigger, so we now run a box around the map to trim off any of the pink dem edges to make it straight sided, otherwise it won't load into the Scenery Designer. If it doesn't load and says no data, retrim the edges as you may have missed a trace of pink dem on edge.
In scenery Designer it is New and open the dem map you just saved, etc.
I just import the colours from another of my maps. Also I made a coloured bitmap to replace the greyscale bitmap that makes the terrain. However we can only have one so tried to include, rock,sand and grass.
I set the size of this about 250 as I think the default is a 100.
Use any of my settings from my sceneries, and the coloured bitmap, if any use.
It sounds complex but it just a case of clicking on the buttons I mentioned with the names given.
Jeroen from Stentec explained the procedure to me on the forum.
Also I worked through the sequences as I typed them so I reckon not counting depths, terrain could be made in less than half an hour of any available area if you have the files downloaded.
Altug discovered about 2048 in the box to get the maximum resolution.
Just post if you get lost on it as took me a" little while" to get the sequence correct.
Also you can open up rivers, etc as previosuly detailed but again post for more info.
Setting no data to 1,2,3 metres working along the river, drawing a box around each section first as only that area is then altered.
Best to keep maps small to get nice detail. About 25 miles and preferably under 50.
Any missing islets or terrain, you can put them in by hand, fill in any gaps with ajacent height pixels. click twice on new first new pixel height you place otherwise it uses previous height.
Time for another sherry I think.