Help on transform a map to GIS

I need to create a geographic map for a game. Usually I draw it on
paper by pencil or watermark in an artistic way. But at this time I
need to create a map following some sketch make by others, and
draw it as accurate as I can. This means that I have to recreate
sea, mountains, lakes and import it on a computer for further
elaborations. My question is, how I can perform it to obatin something
readable by a Gis software? at the end I need to allocate information
on this map (streets, building, resources, etc.) in a dinamic way.
I have taken a look of some GIS software, but it is not clear to me,
all the steps starting to the paper drawings to the GIS format.
Someone can help me ?

MEtilico

none@___NOSPAM.it wrote:

Hi,

you would need more though on your problem...
First, GIS stands for Geographic Information System, so there is no "GIS
format". In terms of format, you can display about anything. What
matters is the location of what you are displaying.

You talk about "mountains"... what do you mean by a mountain on a map?
Are you looking for a 3D representation? In this case, you need a DEM,
Digital Elevation Model. Then, you can overlay a map, an image or
whatever over this DEM and have a software to render it in 3D.
Or, you might be talking about elevation contour lines, or just about
colors on your map, or maybe you want to use a symbol, or.... there are
endless possibilities.

Now, if you have a map on paper, you want to 1) scan it and 2)
georeference it, which means telling the computer the geographical
location (latitude longitude (in degrees), or a UTM coordinate (in
meters)) of a few selected points. Then, the computer will be able to
compute the geographical location of any point on the map.
In the real world, it is fairly easy to do.. a street intersection has 1
location that can be measured on the field. In your case, since it is an
imaginary world, you would have to come up with your own locations...
which can introduce some distortions in your image (ex: for any 2
points, you can tell the computer that they are 2 mm apart, or 2000m
apart... it will work well in both cases, but the image will not be
displayed the same way)

Once your image is georeferenced, you can either vectorize it (a lake
becomes a polygon etc), or work with is as an image. Then, you can
easily add information to your map. You want to add a road? create a
georeferenced polygon of the road and put it on top of your image! In
any GIS software, the overlay will be made in function of the
coordinates of each items, so you are guaranteed to have things located
at the right place...

Jean

On Fri, 19 Sep 2008 10:32:15 -0600, Jean H


I need to express it as elevation on a 2D. I don't need a 3D
representation. I could mark the elevation by colors or by elevation
contour lines. the problem is if a software can understand an
elevation count line made by a pencil or if I need to perform this
exercise directly inside a software.
which is it the best way to perform this task?



the master image could be also the one represented inside the
software, so I can agree with any distorsion caused by the software.


Do you have some idea of which software I can use in any steps?
And in which softare I can store the data as final product?

Thank you!
MEtilico

Hi,

answers in the text below


Hum, there are different answers based on the complexity of your map and
of the cash you have... basically, you have 2 options:
1) scan and georeference your map, then try to do a raster to vector
conversion. It might be more complicated than one think, especially if
you have lots of other items on your map! Then, assign an elevation
attribute to each vector contour line and voila. You can use tools such
as Topo to Raster, in ArcGIS (there may be an open source alternative),
to derive an elevation surface. You now know the elevation of any point
in your map.
2) scan and georeference your map, then digitize, by hand, each contour
line. It is easy as you just have to follow the scanned line! ... good
luck if your map covers a large extent!


There are several softwares to do that... commercial would include
ArcGIS and MapInfo. There are free alternatives, such as GVSIG, Grass,
Qgis, uDig etc (google "open source gis")

For saving your data, again, there are lots of possibilities. You can
save your data in a geo-database or in individual files. You can save
your data as vector data (contour lines) or as a raster, an image
(elevation surface). In the first case, the SHAPEFILE format (ArcGIS) is
the most standard one... but you are free to use other ones, like GXML
(XML doc providing the coordinates of every point in the dataset,
basically). For rasters, you can do what you want... you can save your
image as a jpg if you want to! (and have an header file along, providing
information on the location and projection used). Common formats are
also GeoTIFF (header in the file), Erdas Imagine (.img), ENVI (plain
binary files, header in a separate file)... so the real question to ask
is what do you want to do with this file? ... if your game already has
its "geographical engine", send you can find / create a format that
perfectly suits your needs!

Jean