[GRASS-user] shapefile, TIGER, or what for a dlg that is stored in .e00 format

[stephen sefick]

I tried this with points, lines and areas on the .e00 file

v.in.e00 'file=/Users/sefick/Desktop/contours Folder/contours.e00'
type=area vect=georgia_contours --overwrite

importing areas......

unable to open data <source cont>
an error occured. Stop.

what now?

I didn't have any luck with the grid data - tried and gave up.

thanks

Stephen Sefick

On Wed, Jul 8, 2009 at 7:38 PM, Nikos
Alexandris<nikos.alexandris at felis.uni-freiburg.de> wrote:
>
> stephen sefick wrote:
>
>> I am trying to make a DEM from contour lines downloaded from here
>> http://csat.er.usgs.gov/statewide/layers/contours.html
>> I converted this to a shape file
>
> You don't need to convert it to  Shapefile. You can import vector .e00
> files directly in GRASS using v.in.e00. Note that you need to have to
> programs installed: "avce00" and "e00compr".
>
>
>> reprojected it,
>
> why? from what to what CRS? Did you not create a location based on the
> coordinate reference system in which the data are referenced? Did you
> have any success with the "GRID" data, if of course you tried?
>
>
>>  and then v.to.rast use=value and got out a raster with a range of 1
>> to 1.
>
> That is so because the v.to.rast module expects from the user to define
> the "value" incase you use the "use=value" parameter. If the user does
> not define the "value" then "value=1" is taken as default. Please read
> the respective manual(s) [1].
>
> I suppose that "v.to.rast use=val value=SomeValue" is not what you want.
> Giving a fixed value to all of the vector features that will be
> rasterized wont be useful if you want to play further with the data
> (e.g. create a DEM as you mention above).
>
>
>> How do I do this?
>
> --%<---code--%<---
> # I downloaed the data you mention and did the following:
> v.in.e00 contours.e00 vect=contours type=line
>
> # check attribute table
> v.info -c contours
>
> v.info -c contours
> Displaying column types/names for database connection of layer 1:
> INTEGER|cat
> INTEGER|UserId
> INTEGER|FNODE_
> INTEGER|TNODE_
> INTEGER|LPOLY_
> INTEGER|RPOLY_
> DOUBLE PRECISION|LENGTH
> INTEGER|CONTOURS_
> INTEGER|CONTOURS_I
> INTEGER|ELEV
>
> # match region ## I am unsure about the resolution (=look at the
> original data resolution from which the contours derived)
> g.region vect=contours res=SomeResolutionValue -pa
>
> # the last column is probably of your interest, so
> v.to.rast use=val value=attr col=ELEV
> --%<---code--%<---
>
> Perhaps you do not even need to rasterise. Have a look at v.surf.rst
> [2]. Of course I am no expert with DEM's, v.surf.rst might not be what
> you need.
>
> Kind regards, Nikos
> ---
>
> [1] http://grass.osgeo.org/grass64/manuals/html64_user/v.to.rast.html
>
> [2] http://grass.osgeo.org/grass64/manuals/html64_user/v.surf.rst.html
>
>



-- 
Stephen Sefick

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

								-K. Mullis