GEOSTATS: Hexagonal Grids in ARC/INFO
- Thanks to those who pointed the way - Here is the summation
>I am interested in utilizing a stratified hexagonal polygon grid toThe SUMMARY
>define a ground water sampling network. In our shop we utilize ARC/INFO
>for our GIS work. However, none of the GIS gurus I've talked to know of
>a way to generate such a grid. Does anyone have a reference to
>hexagonal grid generation in ARC/INFO?
From: jutsonph@... (Philip Jutson)
You can generate a regular 'grid' of hexagons using the aml program I
included and a little bit of work. This program creates a file that the
command GENERATE can use to create a point coverage (don't forget to
topology). You can then use the arc command THIESSEN to create
polygons. The only problem is that the edge polygons are not regular in
Notes: The AML can be obtained from Philip Jutson. It AML & technique
works just fine
thank you (see the RESULTS at the end).
From: dstewart@... (David J. Stewart)
In the past our lab has been in contact with ESRI, and they have
provided us with a number of amls which we modified and extended to
eventually produce a polygon coverage containing series of
equal-sized, hexagons covering the area of interest. They worked,
sort of, but were extremely cranky and sloooow...
The research described in Pulliam, et al 1992 (Ecol. Appl.
2:165-177) uses this technique but doesn't say much about it.
Since then I've written several C programs that are called from
entirely new amls which work much more efficiently, taking hours
rather than days (or failing) to produce a 3ha cell size grid of
a 780 sq km study area. (The time required to generate the lattice
seems to be exponentially related to the number of cells. Still
not efficient from a computer science perspective, but tractable.)
The first research using the new programs will be presented at
Forest Service conference in May.
So the answer is -- yes, if what you want is a polygon coverage
of adjacent, hexagonal polygons with few attributes beyond cell#,
row, column, and neighbor list. I have other amls which will
establish relates to other polygon coverages, by which attributes
can be transferred.
Note: More discussion was included and I'll send it to anyone who wants
Our local GIS staff had build series of amls for me that generated a
point coverage and
a variable rectangular (or square) grid coverage - then overlayed the
two and gave
output so I could determine what grid cells the points were in. In this
way I could
build a stratified square or rectangular sampling scheme. This
generalized aml was also
needed for ground water modelers, etc. Thus it was made as generalized
The GIS programer decided to incorporate Philip Jutson's aml to build a
The existing amls can overlay and draw the resulting point and hexagonal
A few more tweaks and we'll have the output portion. Unfortunally, he
had to leave for
two weeks of Military Reserve duty!
We'll have the resulting menu-driven aml system - square, rectangular,
polygon and point generation and then coverage comparision done in 4
depending on what fires have to be put out when he gets back.
If anyone wants the final aml system contract Chris Oman at
him for a copy of Osburn's Grid and Point AML.
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