Latest Contributions by SebastianSantibanez

‎01-11-2013

I don't think it's possible to do that in ARC. I would encourage you to do that in python using arcpy.RasterToNumpyArray to transform your raster in an array.

‎12-21-2012

I guess that you could fit some helmets to your geographical features and obtain your saddle point by analyzing the deterministic surface you would obtain from that fitting. Another suggestion I would explore is passing a low pass filter through your raster so your geography gets smoother.

‎12-20-2012

Numpy seems right. take a look a this http://homepages.math.uic.edu/~jan/mcs275/arrays.pdf it has the right algorithm ready for you

‎12-20-2012

Thank you for your answer Erick. Unfortunately the global polynomial method for trend removal did not render the expected results for me (besides the fact that I'm working with "Event" data). I decided to move towards areal interpolation with ancilliary data.

‎12-11-2012

Hello, I am attempting to perform an areal interpolation in some demographic data. The data exhibit a quadratic trend E-W and linear trend N-S. I suspect that the trend is (in part) the reason why the covariance fitting is not successful. Is there any direct way to de-trend my polygon data prior to the Areal Interpolation? Thank you in advance.

‎10-03-2012

Hi, Did you look at "Incremental Spatial Autocorrelation"? This can give you a hint too http://video.esri.com/watch/903/spatial-statistics-best-practices I'm sure there is some reading material about that workshop but I didn't find it.

‎10-03-2012

Chris I haven't started developing the prototype in grass yet, but when I have some news I will share them. As far as concurrent SA processes go; the prototype I built ran a naive algorithm, and after so many unexpected crashes didn't feel like optimizing it. I will try your approach of starting with a raster and see if it makes any difference, maybe after that I will run concurrent processes. Thank you again for your help. PS: The cost surface runs a modified dijkstra's algorithm in the background, right? if so, it might be more efficient to write your own code.

‎10-03-2012

Hi Jason, You need to take a good look at this pages for the selection by wildcard http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//001700000071000000 http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00s500000033000000 Untested, but probably your selection query will look something like '"thefield" LIKE'+"'"+thewildcard+"'" and for updating your values to your new field read this http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00170000004m000000 and this http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Calculate_Field_examples/00170000004s000000/ I hope it helps

‎10-03-2012

Thank you for your comments Chris! I have compressed and uncompressed, compacted and uncompacted and started from scratch in new databases so I'm positive that the error is not there. In my coding I use exactly the same practices you mentioned, with the exception that I normally define the "env extent" inside the loop starting with "SHAPE@XY" +/- the buffer distance (this probably saves me a couple of miliseconds since I don't have to create a buffered feature). Actually, if I'm not mistaken you gave me that idea in a previous post. Anyway, I have been talking with a developer about this error and we agree that the debugging is going to be tedious and probably will not lead us to a permanent solution. So we have decided to translate this part of the development to R.cost (the grass module). I tested R.cost in grass and I would say that it runs at least 5X faster than arcgis. As a side note, maybe you want to consider processing your cost distances in block. Select a subset of points far enough from each other so the cost distances will not overlap and process them altogether. I haven't tested this approach but in my mind it makes perfect sense... obviously the most complicated part will be creating those subsets (probably a heuristic search algorithm would help) I hope it helps.

‎09-26-2012

Did you accidently run the Compress tool on that FGDB (thereby making it read only)? FYI: Many raster functions (inclusing CostDistance) still operate significantly faster in GRID format vs FGDB raster format. Thank you for your input Chris. No compress tool was ever applied to the FGDBs. Besides, I have restarted the process from new FGDBs and keep encountering the same problem.

‎09-24-2012

Hi all, I'm experiencing this random error when I run a record-iterated cost distance script in arcpy. The code I have used to work well in arcgis 10.0, but now in 10.1 is giving me only headaches. I want to outline that the code fails randomly at different stages of the iteration, however it has never gone past the 200th record. Traceback (most recent call last): File "C:\Users\urban4m_02\Documents\MSAu4m\py_codes\cost_dist_norm.py", line 67, in <module> outCostDist = CostDistance(row[2], cost, maxDist*factor) File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Functions.py", line 640, in CostDistance out_backlink_raster) File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Utils.py", line 47, in swapper result = wrapper(*args, **kwargs) File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Functions.py", line 634, in wrapper out_backlink_raster) File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\geoprocessing\_base.py", line 484, in <lambda> return lambda *args: val(*gp_fixargs(args, True)) ExecuteError: ERROR 999999: Error executing function. Workspace or data source is read only. Workspace or data source is read only. ERROR 010029: Unable to create the raster C:\Users\urban4m_02\Documents\MSAu4m\scratch.gdb\CostDis_f0F01. Cost Distance mapping Failed ERROR 010067: Error in executing grid expression. Failed to execute (CostDistance). I'm running the iteration using with arcpy.da.SearchCursor(inputFC,["OID@","SHAPE@XY","SHAPE@","ICOUNT"]) as cursor: for row in cursor: outCost = CostDistance(row[2], costSurface, maxDist) ... and I have tried fixing it by adding cursor.reset() arcpy.CompressFileGeodatabaseData_management gc.collect() but no luck so far. Has anybody else experienced similar issues when running an iterated spatial analyst tool in arcpy?

‎05-30-2012

You could try transforming the raster into an array using arcpy.RasterToNumPyArray. From there is just sorting the array and read the value contained in the position (9,999). When you know this value you can use raster calculator in order to generate a new raster with the top 10,000 values of your raster. I hope it helps

‎02-24-2012

Hi Graham, You should expect an offset of several meters between those GRS (there is a button that looks like a ruler in your toolbar that you could use to measure the distance between redundant features in both layers). You should always consider the scale/resolution of your original data when you assess the match in a transformation of GRS (do not expect a great match from low-scale cartography). If you need a better match the only idea I can suggest is that you perform a geometric transformation based on some common features that you could identify in both layers. I hope it helps.

‎01-24-2012

Why not getting some points with known coordinates in both systems and calculate your own parameters? If the area is not that big, a 2D transformation will do just fine.

‎10-11-2011

I had problems combining batch and iterators too. The fellows from ESRI advised me to avoid combining these two tools (although there was no further explanation on why...). I ended up not using batch at all and nesting different models when I required more than one iterator (you can just put 1 iterator per model). I hope it helps

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Date Last Visited	‎11-11-2020 02:24 AM

My Ideas

Latest Contributions by SebastianSantibanez

Re: multicollinearity and VIF of raster variables

Re: [Cross-post Python forum] Finding saddle points in a grid?

Re: [Cross-post Python forum] Finding saddle points in a grid?

Re: Areal Interpolation AND trend

Areal Interpolation AND trend

Re: GWR settings: bandwidth parameter

Re: Arcp randomly crashes when runing iterated cost distance tool (spatial analyst)

Re: Update Cursor using wildcards

Re: Arcp randomly crashes when runing iterated cost distance tool (spatial analyst)

Re: Arcp randomly crashes when runing iterated cost distance tool (spatial analyst)

Arcp randomly crashes when runing iterated cost distance tool (spatial analyst)

Re: Select X number of maximum value grid cells

Re: Geographic coordinate system issues

Re: Georeferencing to an Unknown Coordinate System

Re: Writing file names automatically when using batch tools