07/26/03 |
If you want to try to make your own terrain maps, it's pretty easy to do. You will need a free program called MicroDEM, a good photo editing program that can adjust brigtness and contrast and also tell you what the color levles are in RGB values.
You will also need some Digital Elevation Model (DEM) data. For US you can get it free from http://edc.usgs.gov/glis/hyper/guide/1_dgr_demfig/index1m.html or http://seamless.usgs.gov/ The SRTM data at the second website looks like it might be little bit better but it may have holes so you may just be best off using the NED data from second website. I think the NED data is a little better than what's on the first website.
If you are using the second website, you must make sure to download the data in the correct format. Just zoom into the area you want and select the area to download. Then a window will popup with the download link. Before you download it, click on button called "Modify Data Request". Then Select the option as shown below to download it in TIFF format.
Then click on Save Changes & Return To Summary button to download the data. When you go to import it with MicroDEM you have to select File|Open Dem and then select the file type to GeoTIFF.
For outside US, you are probably out of luck until JPL releases the rest of the SRTM data, which given the extra security concerns over 911 probably will never happen. You can always do a search for DEM or Digital Elevation Model and your country to see if there is anything for your area. When looking for DEM data, anything less than 90 meter spacing probably won't be of much use. There is some data that covers the whole world with 1km spacing, but it wouldn't be of much use given the scale. If you know of some other good sources of DEM data let me know and I'll post it here.
Once you get your DEM data, open up MicroDEM and open the DEM file. Most of the formats can be opened just by going to File/Open DEM. Some formats need to be imported first which you can do by clicking on In/Out button to bring up Data Manipulation screen and then click on import which should give you something like this:
Next right click on the image somewhere and select "Display Parameter" from the menu that pops up. Then another menu will pop up, select Elevation which will give you something that looks like:
However, we want it to be greyscale, not color so right click on it again and select Elevation Colors which will make another menu pop up an select Colors. Then select Gray Scale. You can also check Ocean Check which will have MicroDEM try to determine if you have any ocean and it will color that blue. This comes in handy later. Lake Check usually doesn't work so don't check that.
Once you do this your DEM should now look like:
Next use the buttons at the top of this screen to select the specific region you want to import into SC4. The 4th button from left lets you zoom into a box and the magnifying glasses let you zoom in and out. You will need to compare the DEM to a street map or something to figure out where exactly your city is located and the scale. You want it to be a scale of about 10-12 miles on each side if you want it to match up with SC4 scale. Of course if you are just trying to make a cool terrain and not worried about the scale, this doesn't matter. In the image above, the blackest area is a river or valley and the white area is a mountain peak. Also, zoom in a couple extra times to make sure the image you export is greater than 1025x1025 in size. Usually if you zoom in 4x that will do it.
Another little trick you can do is to right click on the image, select Colors and then select Specify. This allows you to change the color range of the DEM. This might be useful if the DEM imports into SC4 and the mountains are too high or not high enough. Basically if you want the mountains to be low make it darker, if you want them to be higher make it lighter.
To export it, you can either go to file menu and select Save Map as GEOTIFF or you can just right click on the DEM and select Edit if you have your photo program set up as default editor.
Next use your photo editing software (I'm assuming you have Photoshop, otherwise instructions may differ a little) and first resize the image so it is exactly 1025x1025 pixels. You will also have to crop off the scale bar at the bottom, which imports from MicroDEM.
Next, make sure the image is in RGB mode and use the color picker to move around the image and notice that the RGB values change from 0 to 255. Try to find the lowest (blackest) and highest (whitest) points on the image and make a note of those values. Also determine where you want water to be. Most likely the water will be the darkest area.
If you don't have any water at all then you don't need to do anything further adjusting of brightness or contrast. If you do have water you need to figure out at what level the water is at in the DEM and then subtract that number from 85 and increase brightness by that amount. For example if water is at brightness level of 10 you would want to increase brightness by about 74 or 75. Then What I do is fill the water elevation with a color that is about 75. This makes it so the water is deep enough.
If you have mountains in the area you can also adjust the contrast to make sure the highest point is level of 255. You will need to play around a little with brightness and contrast to get it just right, but this should get you started. Also, you can add rivers and streams by painting lines with level of 75-80.
Also, if you had MicroDEM make the Ocean blue, then you can fill those areas with grey scale brightness level of less than 85 to turn those areas into water.
Once you are done changing the image, convert it to a 8 bit greyscale and save it as BMP or JPG. That's it.
Here is a catalog of international DEM data. It's kind of old but may be of some use to people trying to make their own.
If you are having problems understanding how to adjust brightness and contrast when making your own here is some more explanation on how I adjust brightness and contrast.
What I do is first look to see what level the water is at. For example lets
say the water is at brightness of 10 and the lowest land area is at 11. Next
I set the background to a brightness of 1. Then I will use Photoshop to
select all pixels with brightness of 10 and cut them out which leaves water
areas with brightness of 1. Then I go thru an manually fill in some areas
with brightness of 1 if I want to add some more rivers or something.
At that point I have a pretty good difference between water and land which
will make sure the water is a little deeper than just 1. Then I increase the
brightness of the whole image to make the lowest land be level of 86. So in
this case I would increase brightness by 75 since the lowest land are was
originally 11. This leaves the lowest land area at 86 and the water would at
76.
The other thing to watch out for is to make sure when you increase
brightness it doesn't leave all your mountain tops flat. If you have a lot
of areas with a high brightness of over level of 200 and you increase the
brightness by 75 it will flatten out the tops of your mountains because
large areas will end up with level of 255. If you have this problem you
first want to make sure and adjust the contrast so you mountain peaks are a
little darker before you increase the brightness.
Also, if you are just going by the greyscale percentage instead of RGB values to determine water level, the water level should be right around 66 or 67%. (1-85/255)
Some Limitations:
Can't have water at different elevations.
Really big mountains may not look as high as they are in reality. If we could figure out a way to get water level down to 20 or 30 instead of 85, we could fix some of this problem.
If you don't mind being forced to use smaller regions,
I highly recommend downloading the USGS 7.5 DEMs. They come in two resolutions,
10X10, and 30X30.
The 10X10 DEMs cover a 7.5 degree area, and are extremely detailed. Since
MicroDEM allows the merging of multiple DEMS, you can 'stitch' a number of the
files together to create a larger region.
Check out the screenshot below. This is taken from the 'high resolution' 10x10
DEM of Easton, PA.
If you notice, on the high-resolution file, lake-check actually *works*... this
is nifty in that you can then keep your lakes and rivers when you import the
city into the game. Also note, on the 7.5 degree DEMs, they're detailed enough
that you can actually make out highway cloverleafs in the image that's produced.
(lower right coner)
The other, REALLY cool thing is that in SimCity4, 1 KM = 1 small city in size.
The 10X10 DEMs when saved via MicroDEM as a 1:1 image, work out to a size in
which 100 pixels = 1KM in size. What this
means is that all you need to do with it is trim the file to a multiple of 100
in size (ie, 1000X1000, 1000X1300, etc), go in to do any editing needed, then
resize to fit the SC4 format, and your dimensions will fit exactly to 'real
world' sizing. It saves a LOT of steps.
Since the 'lake check' actually works 95% of the time with the 10x10 DEM files,
you can also go in, polish up the water on the map that shows as blue, highlight
all of that color, inverse the selection, and tweak your levels so the colors
then become values higher then the 'water line' in SC4 is set at. Inverse again,
so the water is once more selected, change the color to a grey value less then
the 'water line', enlarge the image to the requirement needed by SC4, and
boom... instant terrain.
I know this sounds complicated, but it saves about 75% of the drudgework usually
entailed in making the maps.
Heh. Helps if I actually post the link to where the 7.5's are...
http://www.atdi-us.com/
What you'll need ahead of time: a map with latitude and longitude on it, down to
the arc-minutes (ie, pretty precise). You'll need to punch the
latitude/longitude in to the site to get the desired location.
Here's a quick equation you may find useful for
getting the right height scale when importing maps:
Contrast = 100 (-1 + (((Hmax - Hmin) / C)) / (Smax - Smin))
Where:
Hmax is the height in meters of the highest land on your map.
Hmin is the height in meters of the lowest land on your map (will be 0 for maps
with oceans).
Smax is the shade (0-255) of the highest land on your map.
Smin is the shade (0-255) of the lowest land on your map.
C is the ratio of height to shade. It is a constant equal to approximately 2.65
Once you get the contrast, edit your map in Photoshop and set the Contrast equal
to that number. Once you get that, you'll have to play around with the
brightness to get the water at the right level.
I've only tested this formula for maps where the total range must be reduced. It
might work for other cases too.
This site was last updated 02/03/03