12,599 reputation
1167157
bio website maphew.com
location Yukon Territory, Canada
age
visits member for 4 years, 9 months
seen 13 hours ago

hewer of maps, old time techie, newbie developer

woohoo, http://gis.stackexchange.com/ now open to the public!

personal - www.maphew.com
in-between - yukongis.ca
work - www.environmentyukon.ca

profile for matt wilkie on Stack Exchange, a network of free, community-driven Q&A sites


May
16
comment How do I change geotiff “no data” color to white/transparent rather than black?
@alfonx, yes there's a difference between a cell that's recorded as nodata and cell that says I am 0 and the application decides whether it or some other value should be ignored. ArcGIS does respect the results of gdalsetnull.py; I've no experience with GeoServer.
May
16
comment How do I change geotiff “no data” color to white/transparent rather than black?
there is no link in your text.
May
16
comment Interpolating heights in DEM using ArcGIS API's in C#
@rk01, sorry I don't use the api so can't comment on that part.
May
12
comment How to account for Colour Blindness when designing maps?
Thanks for the reference George, that looks like a good document, though I only skimmed it as I'm pressed for time today. To improve your answer you could include an executive summary (precis) of what the document is about, it's primary ideas (c.f.microcontent)
May
11
comment Methodology for creating accurate drainage networks (and catchments) from high resolution LiDAR DEM?
perhaps I'm mistaken, but doesn't Lidar include tree canopy height? that might be throwing flow analysis for a loop. My biggest hunch though is that your cell (pixel) size is too small. It's initially counterintuitive, but I've discovered in other places that using a cell size which is supposedly less precise can yield more accurate results.
May
10
comment Interpolating heights in DEM using ArcGIS API's in C#
The USGS DEM file format is an interchange format and not designed to be used in place. It's a medium to transfer from one place (program) to another. The process of creating a grid from the .dem file, using the conversion tools, will result in a continuous surface - a model with no gaps (but can include "nodata" cells) - which you can then run your C# code against. I don't think the ArcGIS API will operate directly against the .dem file.
May
10
comment Interpolating heights in DEM using ArcGIS API's in C#
Usually a DEM is already "interpolated", meaning it is a continuous raster surface, what format is yours in? If it's an ascii text file commonly called USGS DEM format or similar all you might need to do is run the DEM to Grid or Ascii to Grid tools (in the Conversion Tools toolbox) to create an interpolated surface.
May
9
comment Quality of free geodata compared to commercial sources
With respect to the tile of the question: you can't compare generic "free" and "commercial" data and get a meaningful answer. The field is too wide, and the free/commercial distinction is orthagonal in any case. Some commercial data sets are worse than horrible, others are beyond compare. We could get meaningful answers by asking "how does XXX compare with YYY (for the purpose of ZZZ)?".
May
9
comment Fastest way to create an ESRI Grid and populate cell values?
A small sample of what the ascii files actually look like would help. A verbal description is not enough to account for the variable ways it could be interpreted.
May
4
comment Error assessment of calculation done using unprojected vs. projected data
Thank you for this and prior question. It's important to have theory/basic-principles discussions that are software agnostic as well as "how can I make program-x do y?". I just wish I were better capable of understanding their depth and details. ;-)
May
3
comment difference between Simple and Attributed relationship classes?
thanks for the article reference. I found it helpful for setting context and extending my understanding of how Esri vocabulary differs and matches db talk seen in other places.
May
3
comment difference between Simple and Attributed relationship classes?
just to be clear, the pro and con you've outlined applies to both kinds of RC, right?
Apr
28
comment Getting started with Arcobjects
re:field aliases - you should add that as an answer to the Q. I didn't know that was possible.
Apr
28
comment How do I draw on a vector map in GRASS?
Nice. I didn't know there was a collection of video turorials. I'd fold the comment into your answer so it's all in one place (use the edit link in grey under the post)
Apr
27
comment Getting started with Arcobjects
I have ArcGIS 9 & 10. I haven't selected any development software.
Apr
27
comment The general public and their ability to use GIS applications - do we still need paper maps?
Since then I've seen many more instances where people were using computers to capture information, and they really should have been using pen and paper, because they know how to use them. No training, no bugs, no forgetting to save, no fuss, no problem. A little more work at the end for when the info does need to be digitized, but when the whole workflow is looked at and considered, a benefit. In the end deciding on paper or 'pooter really depends on the nature of the information and work.
Apr
27
comment The general public and their ability to use GIS applications - do we still need paper maps?
I once spent a few hours creating a quality map to a friend's fortieth birthday bash. Nice clear fonts and arrows, driving directions and distances, contours, watercourses, orthophoto background, the full treatment. I printed the final draft and sat back with a satisified smile. It was more than a map, this was cartography. And then I slowly realised that for the purpose at hand -- helping people find a party -- the quickly sketched black marker on a napkin model I started with, was much better suited to the task.
Apr
27
comment How do I draw on a vector map in GRASS?
Please also indicate how qgis might be used in this example. Otherwise one could just as easily say "this is nice use case for using Mapinfo for ...", or any other of the hundreds of programs which can edit and join lines.
Apr
27
comment Getting started with Arcobjects
this is a recycled question from Stack Overflow, (ref)which for whatever reason they've decided not to migrate here. So I'm asking again to get more comprehensive answer from the people in a better position to help.
Apr
26
comment Site to download al USGS Topo Maps in bulk
Perhaps see wiki.openstreetmap.org/wiki/Downloading_data for nabbing OSM data in larger pieces, and then of course the TopoOSM page you reference for a workflow.