On Tue, 6 Jun 1995, Jeff Olsenholler wrote:
> Arc 7.0.3 on an HP-UX workstation. I want to make a polygon coverage
> from a grid. Here's the description, the command and the result. I, and
> my colleagues, are clueless. Anyone care to inform us as to what's up?

Thanks to Wylie Burt, Elizabeth Cheney, William E. Diego, Bill Baillargeon,
and Graham Donald for taking the time to respond.

A cigar to J.Brainard@uea.ac.uk for the winning suggestion:

>I expect that someone will give you a more precise answer., but
>I have found that Arc is very flakey with small values ( << 1).
>You have cellsizes which are much less than 1, as you seem to be
>working in lat/long coordinates. When I had to put together very
>large datasets in lat/long it took me ages and I had to do it in bits
>because the software kept choking. I tried double precision, too,
>to no avail.

>Can you try transforming your grid to something like lat/long
>seconds, converting it to a polygon coverage, and transforming
>it back to decimal degrees (or whatever you're using). Might be
>a viable work around, at least.

Well, I gave it a shot:

Project: output
Project: projection geographic
Project: units dm
Project: spheroid wgs84
Project: parameters
Project: end
Project...
Arc: describe popdm
Description of Grid
/AUTO/NFS/NASA/PROJECTS/SEDAC-2.2/WORK/JOLSENHO/WALDO/POPDM

Cell Size = 5.000 Data Type: Integer
Number of Rows = 1548 No Value Attribute Table
Number of Columns = 4320 Attribute Data (bytes) =-1

BOUNDARY STATISTICS

Xmin = -10799.996 Minimum Value = 0.000
Xmax = 10799.996 Maximum Value = 2794792.000
Ymin = -3419.999 Mean= 2689.602
Ymax = 4319.998 Standard Deviation = 12345.409

COORDINATE SYSTEM DESCRIPTION

Projection GEOGRAPHIC
Units DM Spheroid WGS84
Parameters: