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Anyone has tutorial on Basic DEM

PostPosted: Fri 01 Sep 2006 - 00:59
by BillC21
BasicDEm looks like a good candidate for making DEMs. You can download the the DEM Calculator details on where to get it . Go to the web site . Garry Petrie 19880 Nestucca Drive Portland, Oregon 97229 USA. Email Tel: 503 264 3027. Reading this so far you would think I know a lot about UTM fields Virtual Terrain Modeling. Really I don't know just a basic learner. However if I can get through to Gary which I am unable to do so far I will start from the beginning and write the procedure simple so that all of us can understand. The Downloads you can get on the web site consists of a BasicDEM Viewer and a Basic Dem Calculator. Its a shareware program and one should register and give a small donation. As I mentioned I cannot get word or email from Garry ,. He could be on vacation. Any interest or knowledge on BasicDems would be appreciated. Another approach is I have just bought Paint Shop Pro 8.0 and start with scanning a nautical chart small area to start and give it a file name and put it into Paintshop pro. Use a transparent layer over the chart and enter numbered contours. Then switch to grayscale. Name it a BMP file and import it into Scenery Builder Sail Simulator. I have not started this approach yet but again anyone expert in this approach could get back to me with any information in clear understandable English. Regards Billc21

PostPosted: Fri 01 Sep 2006 - 08:30
by Barry


I just use the dem that we have in the Scenery Designer.
Either tracing contours over a chart or map.
However depending on the area you are making satellite data is the easiest.
I use srtm2 data. Free to download.
Terrain can be very easily generated and you still have to lay the depths.

The terrain itself can be be made in about 15 to 30 minutes.
Say 20 miles to 100 miles, but smaller areas give better resolution.
However you need to lay the depths by hand and that can take time.
There are full tutorials on my site and all details.
Plus links for 3dem, satellite data, etc.

Download 3DEM. change to utm projection from ellipsoid.Convert to bt file with virtual terrain and set size. Import into dem editor and terrain is ready for generating.
Make no data 0, which makes all the water a blank dem to lay some depths. Rivers can be opened up with drawing a box around each area in stages and setting no data to 1, 2, 3, etc as you work along the river.
Low lying areas such as the Thames Estuary, do not work well and terrain needs to be a bit hilly.

Although the resolution of srtm2 data is coarse by combining it with the dem editor, the pixel size is reasonable for rivers and estuaries.

However if there are other methods any easier, with full details would be interested, plus step by step details in tutorial form.

You need the full dem editor not the demo, and to save a dem map you need to make it compatible to windows 95.


Dems for Scenery Designer using BasicDEM ,Paint Shop Pro 8.

PostPosted: Fri 01 Sep 2006 - 19:38
by BillC21
Barry nice to hear from you . I have had about a 6 months break since I am teaching and writing a book on C++ for High School Students. First may I congratulate you on the excellent terrain and land structures , Done a great job Barry. Let me discuss another possibility which I briefly discussed in the last discussion . BasicDEM ( Garry Petrie). It's a shareware program and somewhat tutorial. THe interesting part is the Calculator window which when you enter the parametersLongitude Latitude E/W (UTM) N/S(UTM) Elevation Declination et al the calculastor automatically generates a map view and a BMP file is generated . The Virtual Terrain Modelling is wxcellent. I have not been able to contasct Garry however I was able to download the file via The other approach I mentioned Barry is that I bought Paint Shop Pro 8.0 and will put a USCG map on my scanner and file it in Paint Shop . I have not tried it yet burt will keep you informed. What I think the problem is that we do not get too many members interested in DEMS is that the descriptions are too complex to perform and most do not have the time. Now let me address generating DEMS using the Stentec DEM builder. I find Barry that if you draw the contour lines that the finished contour lines are JAGGED if you enlarge the window to get more accuracy you only succeed in making the contour lines more jagged. The finished product in Scenery designe is really not shoreline not smooth but jagged. I have at the stage of preparing DEMS which have smooth contour lines . Perhaps you can discuss that Barry. I will look at your site and comment on it next time around.AS I mentioned Barry I think Garrys approach is the best just putting the numbers into Terraib Calculator and let it do all the work . Bill Cridland

PostPosted: Fri 01 Sep 2006 - 21:02
by Barry
Hi Bill

Tracing contours is a bit of an ordeal but try the satellite hgt data method if you havn't already tried it, as I no longer use the contour tracing method.

No sure what countries as well as Europe it covers, but I am using Eurasia srtm2.
This have been repaired for voids, etc, free and the the latest version.
Although I think it's 90 metres resolution, which doesn't open up the narrower rivers, there are ways around it.

The Conway river at about 20 mile dem has a pixel size of about 20 metre I think so you can always add or delete bits that arn't correct to make it more realistic. The original hgt pixel size is I think 90 metres. However a nice smooth scenery can be produced depending on size.

Not keen on shareware programs, so will probably stick to srtm2 data. Also don't have paint shop pro, etc, as I think you need a program with embedded height for bitmaps.

Just a matter of clicking on the right buttons and the terrain generates automatically from the greyscale map. Only takes say 15 to 30 minutes the basic greyscale using hgt data. No tracing contours except to lay depths using whatever preferred method.

Depths are the problem but depends how accurate you want to be, so hours for me but you could spend weeks.months getting them correct, and depending on the size of map 20 to 100s of miles..

I have tried Virtual sailor and the hgt satellite file immediately converts into a bitmap once you put it into a folder and the route is made, and I the use the colour dropper to fill in misssed bits etc, but again you still have to make a depth bitmap
But I am keeping to Stentec simulators as no real problems now except it needs updating, etc.

Very few seem interested in satellite data, or scenery making, and only know of Altug who has tried srtm2.
Stentec mentioned November I think for SS5
and a new scenery designer was mentioned...but no idea what the present position is as no news for months.

All my routes on the Stentec Server for download I made using satellite data, and the latest Conway river one on my site at present, say just half an hour to make the greyscale to generate the terrain, but more hours for depths and widening rivers, etc, plus a few more hours to make some fresh content.


P.S I had a look at the site link you gave but to be honest looks more complex than the present method I am using, as all the work is done for you already, except depths using 3dem.

3dem enters the co-ordinates automatically and you can join or crop whatever sections of the satellite data you want with a few mouse clicks.

Virtual terrain converts the file to .bt except you just enter 2048 in the max length of map box, and the other box is less, depending on the fraction given for you.

This imports into Stentec dem editor automatically as greyscale with heights. and click no data at 0 makes the blank dem for water, which is shown as 0 terrain at first.

Would be interesting if you could mark the course of rivers over the greyscale to make opening rivers up easier. I just draw a box around the course working along it, and set no data1,2,3, etc which gradually opens it up.

Also if depths could be applied automatically would be good, but no idea how to do that, as depth map and terrain map would need lining up, both identical size, etc.




PostPosted: Sat 02 Sep 2006 - 18:05
by BillC21
Barry I have decided to go to the route you have siuggested that is the 3DEM route. I have downloaded the 3DEM program and have an icon on my desktop. Clicking on it brings up a blank page . Which is ok since I have not pulled down a file yet. The Help I have studied but need your pratcical advice Barry. First Did you choose a SDTS DEM !.Also did you use a type STRM Data DEM File.Where did you store it ?. I have to load a file and the small map I want is Marblehead Harbor and Salem Harbor. MA Would you take me through the procedure slowly. I would say need area of 20 miles by 20 miles.If I can get that far will be very pleased Barry. May I say not sure where we all would be if you were not on line Barry.If we can get the procedure written with the accompanying photos of the windows it will encourage others to get in the water and test the temp. Bill Cridland


PostPosted: Sat 02 Sep 2006 - 18:11
by BillC21
Sorry forgot to mention comcentrating on the USCG 3DEM when we get to importing the BMP DEM file into scenery designer will use one of Stentec sceneries for coloring. I find that the easiest way and colors seem to merge very well . Manual is not the right way to go . Bill Cridland

PostPosted: Sat 02 Sep 2006 - 20:18
by Barry
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.:wink:



PostPosted: Sat 02 Sep 2006 - 21:36
by BillC21
Barry thanks for info. Got to massachusetts OK and selected the county which in this case is ESSEX. Under ESSEX is a lisys of the communities that have DEM files. I chose Gloucester just a test it's a busy fishing port and founded by a bunch of Cornish fisherman in Colonial days. Also I prefer at this stage Barry just dealking with one file.THere are two files to each downloaded from Gloucester they are 1668350.DEM.SDTS.TAR.GZ
the other is a readable TXT file 1668350.DEM . SDTS.TXT. Text works fb just gives importants specs and parameters like lat long etc.THe main file is DEM of Gloucester ,I have downloaded it ok and put the file into my C director just temporary. When I try to open up the DEM file since it is compressed it goes to my WINZIP 32 program and asks for stuff I dont understand . Anyway I'm stuck trying to uncompress the file. I will have a closer look at the WINZIP files make sure they are working. Barry am I right in saying the DEM downloaded file is COMPRESSED . I think it is , just asking your opinion. Also Do I seem to be doing the right things I selected USGS 7.5 minute Digital Elevation Models. Its convenient Barry because DEMS are catalogued by State, County and Map NamesBefore download. I selected the Digital Elevation Model(DEM) -24k not the DRG Model. Once I get the topographical maps for Gloucester I will see what I have to do next. I know at some point Barry I have to convert this DEM file to BMP. Any help would be appreciated. I will study your run down procedure that you just sent me see if it can help me at this stage. Was the choice Barry of 7.5 Minute the right choice for what I want to do .?These are only tests until I can add refinements. Bill C ps aren't you pleased I've come aboard to stir up interest and when we have both finished everyone will know how to generate a smooth fairly accurate shore line and waterway in narural color

PostPosted: Sat 02 Sep 2006 - 21:41
by Barry
Bill only read your post quck as on line as same time as you.
The ftp files are in the following link foleder

Your files are diffrent and you need another program I think to open them.
File are HGT the ones I use.
Will have a look at what you say.


PostPosted: Sat 02 Sep 2006 - 21:47
by Barry
Edited see later posts

PostPosted: Sat 02 Sep 2006 - 21:53
by Barry
Bill USA folder

see following posts

Maybe there others are better reolution but some you have to buy.
Only know about Eurasia files for Europe and UK but USA is available etc.


Looking at Gov URL

PostPosted: Sat 02 Sep 2006 - 21:56
by BillC21
Barry the URL I am using is this is to get the 7.5 min Dem and Text spec. Now maybe I should start at square one and use the same URL that you are using then we could compare apples with apples. So could you give me the URL that you use to get your DEMS . I thought something was strange Barry when I compared your procedural steps with what I am doing and it did not make sense. I dont mind if the procedure will eventually get me to Lime Street Barry Just testing if I can do that then I can pop over to Gloucester later . Thanks Barry Bill C

PostPosted: Sat 02 Sep 2006 - 22:03
by Barry
Bill I don't know anything about the usa files but I think the usa has a better resolution and europe is 30 minutes which I think is 90 metres and the folder you open is 7.5 minutes 30 metres.

Try it first with the link I gave for the hgt ftp folder for USA, and once you know the process explore the other file system you mention.

I remember when I first started I used the files you mentioned and it need another program to decompress them. i think i downloaded one from the internet but a few years back. Got cpompletely lost at that stage and gave up on it.

So at present can only help as regards hgt files.
Will try a USA one now.


PostPosted: Sat 02 Sep 2006 - 22:05
by Barry
Bill I think our posts are crossing and have added bits to other posts but USA FOLDER hgt is ... th_America

See previous few posts.



PostPosted: Sat 02 Sep 2006 - 22:25
by BillC21
Barry have a go yourself see if when you download the 7.5 min you get a problem with WINZIP if so I know it's them . I sent you the 7.5 Min file on last email . I agree you are right Barry if we can get the 7.5 working the resolution will be much better . ASs I mentioned I will go over your procedure and use your files. I f you attemp to do what I just did the County is ESSEX and State is Massachusetts just click on the map to start Barry. When you download the compressed file looks ofk and they put it into the main directory C: which is ok to start then try and open their downloaded file and see what happens Regards appreciate ur help Barry and at least I am learning as I go along . Bill C