Distribution maps - basic help needed
R.Raven at MAILBOX.UQ.OZ.AU
Sun Oct 29 13:15:39 CST 1995
> The data from which our map points are drawn are not
> "computerized" in any way. All are U.S. distributions, ranging
Four years ago we produced an Altas of the frogs, reptiles, birds &
mammals of Queensland. ABout 1200 species, one species per map. We had
the advantage of having the data already on disk,
even thne it was a very demanding task. Since then
GIS programs have advanced. One of the possibilities
now is to scan the maps as bitmaps and use a GIS
program than can "register" the bit map against its
records. You effectively overlay the bitmap with a
vector map and digitise from it. I know ARCINFO can
do that and so can Explorer & Spans. Even then I do
not envy your task. You do not tell us whether the
sources maps are at the same projection which would
simpliy tings somewhat. I believe Mapinfo's present
incarnation in Windoze may do the task also but I
cannot speak with authority. We were absolutely
disgusted with Mapnfo 2 for windoze and haven't
upgraded since. Our atlas was done on the DOS Mapinfo
and was made much less painless because we had data
digitised and had the map plotting automated by a
sophisticated version of C (Mapcode) which handled
the map printing. We would print 40 maps on an A1
plotter in one hour so the entire 1200 went fairly
quickly. We used R:base to generate the point and
remarkably to control where on the page the next map
was to be plotted.
> from local endemics to widespread "weedy" taxa. We will be
> working from "draft maps" on which errors have just been
> scratched through, and several taxa (up to four) appear on a
> single map indicated by different colored dots. Also the draft
> base maps are regional, with many taxa now spread across two or
> more maps. We visualize the finished maps as: 1) perhaps several
> taxa per map, but each taxon on only one map, 2) map should
> indicate distribution at least to county by "dots" (various
> symbols to represent different taxa on a map), 3) showing the
> entire U.S. on the map for widespread species, but smaller areas
> for more localized taxa.
We also did something like this for a World heritage report listing and
it is much more complex because the mapping program should be governed
to a fixed number of scales and then it decides whether an entire species
distribution will fit on scale A or it must select a higher scale.
> How can we best/most efficiently tackle this project? Should we
> do these "by hand", working with a symbols template on a "paper"
> base map? If we can find an "object-oriented" map file, would
> that be the best way to go? Should we digitize the data, even
> though we don't foresee a future use for these files? Can we
> "scan in" the drafts, clean them up, and piece them together to
> create usable maps?
The other process is to have a GIS program that has your projection,
place a map on a digitiser and register the printed map against the on
screen map (about 5 minutes on a DOS GIS) then digitise the points
straight in (about 30 secs max. per point). The bottom line a a GIS which
you KNOW will do the task, not one that a salesman says will do the task.
Dr Robert J. Raven
Museum Scientist (Arachnology)
Queensland Museum, Grey St, South Brisbane, 4101, Q.
Queensland Museum, PO Box 3300, South Brisbane, 4101, Q.
Phone: 61-7-38407698 or 61-18-748 467 (24 hour)
Fax: 61-7-3846 1918
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