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Using validate join helps. I got an error from a field with invalid character: ' ' Solution: I went to excel and replaced space ' ' by nothing -> save .xls -> restart arcmap (yes. no idea why one would have to do this, but otherwise excel edits don't update, even if you remove .xls -fiele and add it again) -> add updated excel after restart -> perform join -> export data
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02-20-2014
10:12 PM
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Using validate join helps. I got an error from a field with invalid character: ' ' Solution: I went to excel and replaced space ' ' by nothing -> save .xls -> restart arcmap (yes. no idea why one would have to do this, but otherwise excel edits don't update, even if you remove .xls -fiele and add it again) -> add updated excel after restart -> perform join -> export data
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02-20-2014
09:47 PM
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Hi, I did everything mentioned here, but yet I got this error: [ATTACH=CONFIG]31504[/ATTACH] As you can see I tried to do basic terrain preprocessing. I placed my data (GRID named testdem) to C:\work\ and set targets to C:\work\ (raster) and C:\work\testing.gdb (vector) I also set processing extent to the extent of testdem, disabled background processing threw some salt over my shoulder and yet I got this error. After that I moved my testing.mxd to the same folder I was able to ran the sink evaluation tool with success. How ever the same tool still fails when using Basic terrain processing... # SOLUTION # 1. I also needed to change the default workspace from C:\ESRI\...\default.gdb to C:\work\testing.gdb. 2. I also changed my dataframe name to "data" to avoid any conflicts (see below). I was wondering why the default paths keep having my data frame name in the paths? i.e. the vector outputs by default are going to C:\work\testing.gdb\MY DATA FRAME NAME\OutPutFile Any ideas on this?
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02-16-2014
10:38 PM
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[/HR] In case anyone else happens to stumble upon this same error, here's what I did to fix it (thanks to ESRI support!): - Disable background geoprocessing - Use a DEM in a grid file format (simply export it out of the GDB) that is located in a root folder (ex. "C:/yourdata/dem") I'm not sure, however, if it was a combination of both procedures or just the DEM in a grid file format in a root folder. Can't go wrong with both of them though! I got the same error with DEM.tif. I converted it to GRID-format, but that didn't help either. Disabling background geoprocessing did the trick, so I was able to get the processses running, but then at the end the process just stucks or crashes when its calculating depression attributes. Tested with ArcMap 10.1 and Arc Hydro 10.1 beta.
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02-14-2014
02:57 AM
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Yep, that's right. Many thanks. It runs through and everything seems logical here and I think this modified script is safer (however all the honors to Pathak for making the original script availalbe in the first place). The original problems (drop-values) remains to be solved. The drop-values are still rounded to 16.666 and to 25 % as I mentioned before. With this new python-script I get less unique values, but still values are rounded up. I sent a piece of DEM to ESRI support to check it out. So let's see. best regards, Henri
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10-29-2013
05:09 AM
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It ran trough, but drop-value problem remains. (noticed a tiling effect, so there might be a projection problem here too -> looking into that currently) best regards, Henri
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10-29-2013
03:04 AM
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Thanks Xander, Good point. I also noted those and had them corrected in my script. I Should've mentioned that. (I'm running ArcGIS 10.1.). Here's the Pathaks code modified : # Import system modules
import arcpy, sys, string, os, arcgisscripting
from arcpy import env
from arcpy.sa import *
# Geoprocessor object
gp = arcgisscripting.create(10.1)
gp.overwriteoutput = 1
#############
# Input DEM #
#############
#set workspace (file directory)
env.workspace = "G:\\xxxx\\LiDAR\\TWI\\"
#set dem name (inside workspace)
InDEM = 'dem_ldm.tif'
arcpy.CheckOutExtension("Spatial")
#Output TWI
rasterOutTWI = "G:\\xxxx\\LiDAR\\TWI\\"
# Load toolbox
gp.AddToolbox("C:/ESRI/Desktop/Desktop10.1/ArcToolbox/Toolboxes/Spatial Analyst Tools.tbx")
########################################################################
# Fill DEM to make it depressionless
outfill = Fill(InDEM)
print "DEM filled"
# Flow Direction
outdrop = "G:\\xxxx\\LiDAR\\TWI\\outdrop"
flow_dir = FlowDirection(outfill, "NORMAL", outdrop)
print "Flow direction raster created successfully"
# Flow Accumulation
flow_accu = FlowAccumulation(flow_dir, "", "FLOAT")
print "Flow accumulation raster created successfully"
# One is added to each pixel to get an count of how many pixel including the current are contributing the flow
plus_raster = Plus(flow_accu, 1)
print "addition raster created successfully"
# Contributing Area using the number of pixels and
Times_raster = Times(plus_raster, 4)
print "multiplication raster created successfully"
# Process: Block Statistics...
Output_Mean_elev_raster = BlockStatistics(outfill, "Rectangle 3 3 CELL", "MINIMUM", "DATA")
print "MIN elevation raster created successfully"
Output_Mean_elev_raster = Minus(Output_Mean_elev_raster, outdrop)
print "EDROP raster created successfully"
Input_false_raster_or_constant_value = "0,005"
Out_change = Con(outdrop, outdrop, Input_false_raster_or_constant_value, "\"VALUE\" >= 0,005")
print "Change elevation raster created successfully"
Input_true_raster_or_constant_value = "2"
false_raster_or_constant_value = "2,828427125"
Out_distance = Con(flow_dir, Input_true_raster_or_constant_value, false_raster_or_constant_value, "\"VALUE\" = 1 OR \"VALUE\" = 4 OR \"VALUE\" = 16 OR \"VALUE\" = 64")
print "Distance raster created successfully"
Out_slope = Divide(Out_change, Out_distance)
print "Slope raster created successfully"
Out_preatan = Divide(Times_raster, Out_slope)
print "Pre-atan raster created successfully"
TWI = Ln(Out_preatan)
print "TWI raster created successfully"
TWI.save("G:\\xxxx\\LiDAR\\TWI\\twi_ykj")
So maybe I should just drop the arcscripting? -Henri
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10-28-2013
10:49 PM
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I'll answer to myself: It seems that all the values are rounded to the nearest 0,5. So 0,401 m / 2.8284 m = 0,14177, would instead be 0,5/3 = 16,6667. Or if distance is 2 metres, then 0,5/2 = 25 %. In the manual it says the values are rounded in FLAT areas, which seems to be a little off considering it does that where slope is 25 %. Another remark is that in flat areas (lakes) the drop percentages are indeed continuous! [ATTACH=CONFIG]28643[/ATTACH] Here's a sample showing what I mean. Darker gray equals flow direcetion to lower left and percentage 16,666 % drop while lighter gray here has 25 % drop and flow direction to the left.
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10-28-2013
02:32 AM
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I'm creating a Topographic Wetness Index using a python script (http://arcscripts.esri.com/details.asp?dbid=16750) As I don't want this just to be a blackbox, I'm trying to understand the different rasters this script produces. One of them is outdrop-raster, which is a by-product of flow direction raster. According to ESRI: "The output drop raster is calculated as the difference in z-value divided by the path length between the cell centers, expressed in percentages. For adjacent cells, this is analogous to the percent slope between cells. Across a flat area, the distance becomes the distance to the nearest cell of lower elevation. The result is a map of percent rise in the path of steepest descent from each cell." ..which seems reasonable. The problem is, that there are several numbers which pop out. For example 16,666.. % and 25 % are by far the most common numbers, why? I'm sure there is an explanation for this, but I just can't figure it out. It doesn't seem logical to have continuous elevation (thus slope) data and results that are not (that) continuous. Original data is low-density LiDAR DEM (2 m pix), values are 32 bit float (197.132, 198.013 m etc.).
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10-25-2013
01:32 AM
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Hello, I started to build a file geodatabase from different point shapefiles. I only got one file imported and then my file geodatabase failed. Yesterday I saved my edits, shut down the computer, and today 5000 out of 5501 observations are gone. With file geodatabase recovery -tool I can see the file how it was yesterday, but I can export only 500 records. The rest is again missing. Yesterday I added data creator and editor fields, I figure they might be the reason behind the corruption? I have a backup in .shp-format, but it doesn't allow NULL values in the fields that I'd like them to be. A working (trustworthy) geodatabase would be nice. Ideas? -Henri (ArcGIS 10.1 sp 1.)
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07-30-2013
11:03 PM
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Got it fixed. We masked out the erroneous 2 pix seamline andthen mosaiced another dem from seamline area with a blend option. Wasn't that fast but it did the trick.
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09-10-2012
04:37 AM
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Hello, I created a raster dataset from numerous DEM's using BLEND as a mosaicing option. However there are still clear seamlines at the edges of the DEM's. I've tried pretty much everything I can imagine to fix this. All the DEM's are made from the same contour and elevation point dataset. (DEM's were made in pieces due memory allocation problems and accuracy reasons -> i'm working with 5 m resolution in a ~2500 km2 area). Do you have any idea how could I blend these DEM's to gether without seamlines? I tried to add layers multiple times to the dataset so more blending would take place, but that's not working.. Could this be fixed via raster calculator? Here's one seamline that can be seen from hillshade: [ATTACH=CONFIG]17544[/ATTACH] Any ideas are welcome..!
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09-07-2012
03:49 AM
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