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[lbiewick at ncrds.er.usgs.gov]

Subject: digital map of South America



I am beginning a project where I will be generating and publishing a digital map of coal in South America using GRASS.  I have scanned the base map on a Tektronix scanner in our GIS lab and saved the data in IGES format because I had planned to use ARCEDIT to transform the data to the coordinate system that the map was generated in (bipolar oblique conic conformal), and then change the projection to something that GRASS will recognize.  I have saved the data in DXF format as well.  I have more layers to scan.

I plan to edit the scanned images using Generic CADD before importing the data into GRASS or MAPGEN.  I am a fairly new GRASS user and am trying to find out the best way to go about doing this.  Any suggestions are welcome.

We have GRASS4.0 running on a SUN 4/380. I can bring my file in DXF format directly into Generic CADD to cleam up the line data, and then bring the DXF file into GRASS with the command v.in.dxf.  Does GRASS recognize bipolar oblique conic conformal projection?  I want to publish the digital map in a projection so that subsequent users of the data can update, change scale, etc.  Can I change the projection in GRASS? If so, what command do I use (proj)?  What would be the best projection to use?  Is it better to assign a projection to the data before I bring it into Generic CADD (say, if I do it as planned using ARCEDIT) or wait 'til just before I bring the data into GRASS?  If I wait until just before I bring it into GRASS, what program do I use to first transform the data to bipolar oblique conic conformal, and then possibly change the projection to something else?

I will appreciate any input I can get as to the best way to go about doing this project.  Thank you for your attention to this matter.

Laura Biewick
lbiewick at ncrds.er.usgs.gov 


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