[GRASS-user] Importing, Defining, and Georeferencing

GRASS GRASS user
,
1

Hello, I’m trying to figure out how to use GRASS (brand new user) and I am having a hard time switching over. I have a TIFF file I want to import and from that create a vector map using georeferencing. Every time I think I’ve imported it correctly, nothing shows up. I’ve done this both before and after creating a new map set, though I don’t know how effective that was. I have been using r.in.gdal, but I don’t know if this is what I want. I know this is a bit of a general question, but I’m a bit lost. Thanks.

Joe

2

Joe

You can import it both ways. Using a predefined location or asking
r.in.gdal to create a new one.

Anyway, you'll get three RASTER maps corresponding to the three colors
chanels (tiff files are raster). If you want a color copy of the input
map youl'll
need to use r.composite to mix them. And if you need a vector map you'll
need to extract features from the raster map thin them and convert to
vector
using r.to.vect.

Juan Carlos Torres

Joe Bayles escribió:

Hello, I'm trying to figure out how to use GRASS (brand new user) and
I am having a hard time switching over. I have a TIFF file I want to
import and from that create a vector map using georeferencing. Every
time I think I've imported it correctly, nothing shows up. I've done
this both before and after creating a new map set, though I don't know
how effective that was. I have been using r.in.gdal, but I don't know
if this is what I want. I know this is a bit of a general question,
but I'm a bit lost. Thanks.

Joe
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3

It seem that you have a tiff instead of a geo-tiff fil.

If you have a tiff file you'll need to import it on an XY location and
then geo-reference it. You can find a clear explanation of the process on

M. Neteler, H. Mitasova: “Open Source GIS: A GRASS GIS Approach”.(3ª
edic.) 2008. Springer.

I have a scheme of the process (in Spanish) on
http://lsi.ugr.es/~jctorres/gis/tema4.html/, slides 5 to 7.

Juan Carlos Torres

Joe Bayles escribió:

I've tried both a predefined location and an undefined XY, either way
the options are throwing me off. When I try to set the extents or
resolution, the functionality won't work, for example, when setting up
a new location or extent or mapset, the N S E W boundaries are set to
1, and I can only change North and South.

Joe Bayles
baylesjm@jmu.edu <mailto:baylesjm@jmu.edu>
joseph.bayles@us.army.mil <mailto:joseph.bayles@us.army.mil>
(703) 677-2539
AIM: joebayles

On Mon, Apr 27, 2009 at 12:02, Juan Carlos Torres Cantero
<jctorres@ugr.es <mailto:jctorres@ugr.es>> wrote:

    Joe

    You can import it both ways. Using a predefined location or asking
    r.in.gdal to create a new one.

    Anyway, you'll get three RASTER maps corresponding to the three colors
    chanels (tiff files are raster). If you want a color copy of the input
    map youl'll
    need to use r.composite to mix them. And if you need a vector map
    you'll
    need to extract features from the raster map thin them and convert to
    vector
    using r.to.vect.

    Juan Carlos Torres

    Joe Bayles escribió:
    > Hello, I'm trying to figure out how to use GRASS (brand new
    user) and
    > I am having a hard time switching over. I have a TIFF file I want to
    > import and from that create a vector map using georeferencing. Every
    > time I think I've imported it correctly, nothing shows up. I've done
    > this both before and after creating a new map set, though I
    don't know
    > how effective that was. I have been using r.in.gdal, but I don't
    know
    > if this is what I want. I know this is a bit of a general question,
    > but I'm a bit lost. Thanks.
    >
    > Joe
    >
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