[CentOS] CentOS, PHP, Basic GIS
Michael A. Peters
mpeters at mac.com
Tue Dec 23 07:44:48 UTC 2008
I have no experience with GIS whatsoever. I really know squat about it.
I'm currently working on a project to plot locality data for wildlife on
a map of Shasta County. This is for a new herpetological club that hopes
to track strength of our local herp populations, since it seems evident
that in the last 20 years we lost one species of frog and are close to
losing another (probably less than 100 left and they don't seem to be
successfully breeding) and the declines were known, but the extent of
the declines was not known well enough until it was too late. We want to
try and prevent that with other species in our county by keeping records
of where they currently are and where they use to be but are no longer
found. When we see what appears to be shrinking range, we can
investigate and if need be, request surveys by wildlife management
before it is too late.
Basically - the data will be plotted as a grid of regular hexagons. When
locality information (museum record or photo voucher record in our own
database) exists, the hexagon the record sits in gets drawn a pretty
color (depending on type and age of records).
I have it working on a raster (jpg) map where I guessed the
latitude/longitude borders - working well enough with sample data that I
know my php code works, but while it is ballpark accurate I need to do
it with maps of known values.
Quick and dirty option - obtain (possibly pay for) a large (at least 2k
pixels wide) raster map with known lat/lon borders that has the county
outline, major lakes and rivers, nothing else. The maps could be made
and then resized for web view. The major problem with that model is that
drawing colored hexagons near the county border and near rivers will
make it more difficult to see them, thus making it harder to interpret
What I would prefer to do -
Draw my data hexagons on a blank slate [ via imagecreate(width,height)
function), then draw the county border on top of that, and then on top
of that either draw the lakes/rivers and/or basic topographical lines.
My preference obviously includes getting data sets for those things
(county border, lakes/rivers, topography) in a format that I can parse
with php to draw them with gd.
My county does have some GIS data available:
I don't have a clue how to get that data into format useful for drawing
with gd via php.
Anyone have experience with this? Can anyone recommend a (preferably
free) Linux GIS program that works on CentOS that could potentially
convert data files into format useful for drawing with gd?
I don't need to get fancy with zoom, rotate, etc. capabilities - just a
basic static flat map output.
Thanks for any suggestions. I may try to find a "GIS for dummies" type
book, though I've generally not been fond of dummy books, I kind of feel
like one when it comes to GIS.
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