38,806 reputation
993168
bio website quantdec.com
location Northeastern US
age 14
visits member for 4 years, 2 months
seen 8 hours ago

Consultant (environmental and spatial stats a specialty), expert witness, and teacher. I can be reached through (outdated but still valid) links posted on my web site.

Twitter: @WilliamAHuber // ASA-P website: http://amstatphilly.org/


Why waste time learning, when ignorance is instantaneous?

--T(iger) Hobbes.

For any complex problem there is a simple solution. And it's always wrong.

--[Mis?]attributed to H.L. Mencken by Dava Sobel, Longitude.


8h
comment How can I make a polyline wrap around the world?
Thank you, @Mike. I love the zig-zag illustration: that is exactly the kind of circumstance I was envisioning while I wrote this answer. If you want a really severe test, see what happens to a polyline that runs along the +-180 degree meridian itself (and crosses both poles)!
13h
comment How do I match two point layers (with different gridding) to a common grid?
More details would be helpful, Andy, in order to develop a clearer picture of what you are attempting to do and the magnitude of the problem. A natural thought is to create a combined model grid (or mesh), but I gather that is not possible (or is prohibitively costly). An illustration showing the two layers could help, too.
15h
comment Extract all unique values from a RGB raster
Does the image come with a legend? That would help immensely, for otherwise you results will merely be a relative rank rather than a genuinely quantitative assessment of the underlying data.
1d
comment creating raster based on 'count' of certain property in 8 underlying rasters
Your request is vague, because (1) you refer to both a class and raster by the same name, "K"; (2) you distinguish one raster "K" as being "new" without explaining what that means for this procedure; and (3) you have not explained what it means by a raster to be "below" another. Could you please clarify these points?
2d
comment Map disappears on Postback
Welcome to our site! I have moved your question to the right location, but you will need to provide some minimal additional information needed for readers to make sense of it, such as what software you are using. When you make those changes, please add appropriate tags.
Oct
21
comment Fitting Time-series Values with a Gaussian Function
@martin That's a good idea. However, to be on topic on stats this question would have to be substantially reformulated, so I don't recommend migrating it. It usually is not constructive to start by giving a procedure that may be irrelevant to the actual research objective, noting that it is failing, and asking how to fix it up. A good question on stats (or anywhere else, for that matter) will explain what the research goal is, describe the data, and ask for specific help in achieving a clearly-stated objective.
Oct
20
comment Fitting Time-series Values with a Gaussian Function
Why do you suppose a Gaussian function ought to fit these values? I rather suspect this fitting might be doing something quite a bit different from what you were hoping for, given that you are using a date of 0 as your initial estimate of the peak (mu) and assuming a width (sigma) of just one day! For some examples and solutions check out stats.stackexchange.com/questions/11546 and stats.stackexchange.com/questions/70870.
Oct
20
reviewed Close How to load Google Satellite images in QGIS using python
Oct
20
reviewed Close Why do pgadmin III views show up as empty ArcSDE geodatabase tables in ArcCatalog?
Oct
20
reviewed Close ArcGIS Desktop Professional Certification - opinions now that it has been a around a few years
Oct
20
awarded  Popular Question
Oct
17
reviewed Reviewed How do I match two point layers (with different gridding) to a common grid?
Oct
17
comment How do I match two point layers (with different gridding) to a common grid?
What is the purpose of the common grid you are trying to create?
Oct
17
reviewed Reviewed How can I match the cells of two rasters?
Oct
17
comment How can I match the cells of two rasters?
Unless these rasters are tiny, outputting a text file will be very inefficient. I just want to encourage you to consider whether that format really is necessary. (It probably isn't if you will continue your analysis in ArcGIS; it might or might not be needed in order to transmit the data to non-GIS software.)
Oct
17
reviewed Looks OK Is it possible to add a service as an item in arcgis online through Arcmap 10.0
Oct
15
revised Regional Large Scale Map Projection Choice
Excised the gratuitious *ad hominem* codicil.
Oct
15
comment Regional Large Scale Map Projection Choice
That statement, @martin f, is not nonsense--it's just wrong. Because UTM is conformal, its scale factor is isotropic (the same in all directions), as you point out in your (nice) answer. Nevertheless, the thrust of the question seems clear.
Oct
14
comment Geometric Operations in GIS Systems
We are not in disagreement. In your example everything will work fine. Yet if you had the same kind of GPS data but were plotting, say, the position of a satellite every hour, your answer might be different: ellipsoidal calculations have obvious merit in that circumstance. As @Ting L claims elsewhere in this thread, all non-metrical geometrical questions--incidence, containment, intersection, separation, and so on--will be solved correctly and efficiently in suitably projected coordinates provided the data are accurately and continuously projected into a connected, simply-connected region.
Oct
14
comment Geometric Operations in GIS Systems
Well, I guess I could have meant either :-). Adopting a basic research principle from historians, I would favor the coordinate system in which the data were created: it has to be considered the original and most accurate. If that's a projected system, use it or be careful about the reprojection process. If it's a geographic system, chances are you might have to project it for many kinds of vector analyses--and once more, as your post shows, take care to project the data well and appropriately.