Input vector data to align with raster

[Cosyn Bart]

Hi,

> Gooday GRASS USERS,
> 
>  I am using the command v.in.dxf to input vector data (IE. roads, bulidings) 
> which has been registered to an aerial photo (USING iNTERGRAPH) ,into GRASS. 
> Unfortunately the vector & raster files are not aligned when I display them 
> in GRASS (ie. roads on vector map do not align with roads on raster map). I 
> welcome any advice to my problem.

I suppose you are using Microstation as graphical module on your 
intergraph machine. My experience with exporting and importing stuff from 
intergraph to grass is rather bad. Not the fact that it should not work 
but it takes much time to transfer. I have no idea how you import or 
export the stuff (Intergraph has an export module to Grass - which I 
never used). Any case I see to possible reasons:

1) The shift is big! Check during the export of your .dxf file in which 
units you are exporting (Major or minor units)

2) The shift is small! What are the extreme coordinates of your raster 
file. Intergraph sometimes takes the middle of the cell as the 4 
cornerpoints, sometimes it takes the real corners. How do you check the 
corner points in intergraph? Be very carefull with taking over the 
cornerpoints given by intergraph. I prefer to check it manually but that 
takes some time.

I hope I can help you with this. Check first these things and try to 
fiddle around with these cornerpoints! Should work!

                        Bart

        ---------------------------------------------------     
        | ir. Bart Cosyn                                  |
        | ERS1/2 project                                  |
        | Laboratory for Hydrology and Water Management   |
        | University of Gent                              |
        | Coupure 653, B-9000 Gent                        |     
     | Belgium                                    |
        | Tel: +/32/9/2646137                             |
        | Fax: +/32/9/2646236                             |     
        | E-mail: bcosyn at allserv.rug.ac.be                |
        | Http: http://sung.rug.ac.be/                    |
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