[GRASSLIST:5089] Re: next step

Michael Ash mash at econs.umass.edu
Wed Nov 27 09:10:22 EST 2002

Thanks for the nice note:
> I read & appreciated your recent "LOCATION ..." post to
> the GRASS mailing list. I'm climbing the same learning
> curve you've been ( leics ...). Tons of commands to
> practice - I don't have a grip yet on the graphic tool
> so I'm command-line bound. But I wonder what's a next
> plausable step after the leics & swordfish intros?

I think that it partly depends on your intended
application(s) of GRASS.  BTW, if by graphic tool, you mean
the menu interface, I don't think that's the most important
tool; however it is, obviously, really important to have the
map display monitor, including the mouse interface for
d.zoom, d.pan, d.what.sites, d.what.rast, d.what.vect

After I felt a bit comfortable with GRASS and the available
GRASS-format datasets, here is how I proceeded:

(1) I created a new location using a common US projection
and datum, e.g., GRS80 and NAD83, and a region with
longitude and latitude values for the US, e.g., for New
England (longitude from 68W to 75W, latitude from 40N to
45N).  Try ew and ns resolutions of 0.1 (degrees) at first.

(2) Then I used s.in.ascii to import to this location and
mapset some simple lists of sites (an ASCII file with each
line containing only (no header or anthing else):

<longitude> <latitude> <label>

Here I used d.sites and d.what.sites to explore the site
map.  Then I used s.to.rast to create raster maps from the
site maps.  (It helps to have the "label" be numeric to see
what the new rasters look like.)

(3) Then I downloaded some free GIS data in .e00 format,
e.g., from the Bureau of the Census
(http://www.census.gov/geo/www/cob/) and imported these data
as vector files with m.in.e00 . (I recommend using areas
that you know well so that you can recognize geographic

By displaying the vector maps with d.vect and simply looking
at the files created, e.g., in dig/, dig_cats/, dig_att/,
dig_plus, I was able to get a better understanding of how
GRASS stores data (although this will change in GRASS 5.1).

I then worked on relabelling the vector maps by renaming or
copying the GIS data to match the dig_cats/ data.  Then I
converted vector data to raster data.

I hope that helps.

Best regards,

Michael Ash

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