All Questions
1,891 questions
8
votes
1
answer
5k
views
Calculating flood volume using LiDAR DEM and HEC-RAS floodplain polygon?
I’ve got a vexing GIS analysis problem which is
conceptually fairly straightforward, but in reality more challenging to figure out….
Basically, I need to calculate the VOLUME of floodwater within a
...
- 81
7
votes
2
answers
984
views
What do ArcGIS regression analysis warnings 000853, 000916 & 000981 mean?
I'm trying to do regression analysis using a shapefile which contains dependent variable (NDVI) and explanatory variable (prec) in ArcGIS.
First, I run GWR analysis and then run spatial ...
- 659
7
votes
1
answer
2k
views
Working around slow processing times in ArcGIS Spatial Analyst functions?
I am batch processing a large amount of distance functions (~50,000) using ArcGIS 9.3. In this version, using spatial analyst functions, it seems to be the case that users cannot parallelize processes ...
- 439
7
votes
3
answers
12k
views
Clipping raster using polyline or polygon using ArcGIS Spatial Analyst?
I have a large raster created from values that cover the whole United States and Alaska which are both polygon and polyline features, this raster was caluclated using Spatial Analyst IDW Interpolation....
- 2,125
7
votes
1
answer
2k
views
What is the "57.29578" that ArcGIS uses in Aspect calculation?
ArcGIS Desktop Help on How Aspect works explains the calculations used, but introduces the for me magic number of 57.29578:
aspect = 57.29578 * atan2 ([dz/dy], -[dz/dx])
Where does this number come ...
- 435
7
votes
2
answers
7k
views
Round Raster to next higher or lower int
I am using ArcGIS 10.1.
I am searching for a solution to calculate a raster.
The values are like:
0.2
0.6
5.3
i.e.
How can I now get 0.2 as 0 and 0.6 to 1 and 5.3 to 5? In the end integer numbers.
...
- 73
7
votes
3
answers
8k
views
Reclassify raster values of 9999 to NoData, leaving all other values alone, in ArcGIS Desktop?
I have a raster in ArcGIS which has a number of cells with the values 9999, showing that the data could not be generated for that cell. I want to convert all of these 9999 values to NoData, so that ...
- 4,014
7
votes
5
answers
2k
views
What type of interpolation to visualize metal detection survey data?
I have about 500,000 points collected in a linear grid pattern over a 1 km2 area. The points were collected as part of a metal detection survey. Each point has X,Y and Coil Response mV (min -675.38 ...
7
votes
1
answer
14k
views
Converting points to raster in ArcGIS?
How do I create such map from point data?
I am using ArcGIS 9.3 and 10
- 1,188
7
votes
2
answers
1k
views
Process a raster with multiple geoprocessing tools in arcgis 10 using python - flow between processes
I'm writing a short python script that includes processing rasters with different geoprocessing tools in ArcGis 10, for example, the three processes below, is this best way to use multiple tools ...
- 427
7
votes
2
answers
4k
views
Can shaded relief be "blended" with DEM colour ramp in ArcGIS to produce a more visually dramatic result?
Not being able to use true transparencies with ArcGIS colour ramps where only solid colours are allowed has me always wondering about how to improve the look of the surface in my maps without ...
- 20.4k
7
votes
1
answer
6k
views
How to exclude outliers from raster using ArcGIS for Desktop?
I calculated terrain curvature from a DEM. The DEM I use is interpolated from point elevation data. Generally, the DEM seems to be good, but some artifacts from interpolation exist. Those artifacts ...
- 203
7
votes
5
answers
3k
views
Georeferencing aerial photos when only centroid is known using ArcGIS for Desktop or ERDAS Imagine?
I have heaps of aerial photos that need to be georeferenced.
I have access to ArcMap and ERDAS.
All I am given is an excel sheet with the centroid coordinates of each image.
Each photo covers ...
- 133
7
votes
3
answers
10k
views
Extract Overlapping Polygon Data to Points
I have a polygon data set of corn yield collected by a combine. However, as the combine drove through the field, there was slight overlap between passes, leading to overlapping polygons within the ...
- 387
7
votes
1
answer
3k
views
Creating all possible polyline routes connecting many point locations around polygon obstruction using ArcGIS Desktop?
Lets say I have 30 ports on the west of an island, and 30 on the east, and need to calculate all possible shipping distances between each and every port, with the routes having to steer around the ...
- 71
7
votes
2
answers
3k
views
Creating shapefile of satellite image footprints?
I'm looking for a tool or a workflow to compute satellite image footprints, for a large number of images across directories, and produce a shapefile. Ideal work flow would be:
fire up tool
point to a ...
- 1,543
7
votes
1
answer
1k
views
How to find nearest neighbors of polylines?
I have a shapefile containing irregularly placed polylines (i.e., survey routes). Following the general idea of a paper I read, I would like to use tessellation to identify the neighbors for each ...
- 73
7
votes
3
answers
4k
views
Calculating area of vegetation in raster file?
How do I calculate area of several vegetation types in a raster (.img file type) image. They are color coded. Am using QGIS (1.8.0) and ERDAS 9.2.
- 79
7
votes
3
answers
1k
views
How to compare spatial patterns (crime cases vs population)?
I am looking for a way to statistically compare two spatial patterns in shape polygon data (not point pattern analysis).
Let's say I have a city map divided in neighborhoods (barrios), in shape ...
- 349
7
votes
2
answers
2k
views
Scratch files left behind by arcpy.sa.Con
I have a Con() statement that creates two "extra" scratch files during it's processing, but that do not get cleaned up once the operation is over and the output is saved.
r=arcpy.sa.Con(elv, ...
- 1,290
7
votes
1
answer
557
views
What are pros and cons of forcing square pixels on reprojection?
I am using Erdas Imagine 2014 to reproject 4-band raster data from GRS 1980 NAD83 Lambert Conformal Conic (ft) to UTM GRS 1980 NAD83 North UTM Zone 11 (m). Unlike ArcGIS, Erdas provides the option to ...
- 51.8k
7
votes
1
answer
2k
views
Are special interpolation techniques required for weather data?
I've downloaded a series of weather observations from the local weather agency - it comprises around 1,000 points spread non-uniformly across Australia, with a greater density of points located near ...
- 21.3k
7
votes
1
answer
851
views
Creating forest patches from land cover layer?
I have a land cover layer from which I've extracted the tree canopy class and set all values that are not tree to NULL. I've also converted it to a vector and exploded it to make single part features. ...
- 71
7
votes
1
answer
1k
views
How to produce a vegetation stress map utilizing the spectral blue shift of the red edge?
I am interested in mapping vegetation stress utilizing the blue shift to the red edge phenomenon in remote sensing. The figure below shows the expected change in reflectance of green leaves under ...
- 51.8k
7
votes
0
answers
1k
views
ArcGIS Kernel Density with polyline, search radius / bandwidth calculation [closed]
I'm conducting a density analysis of a series of polylines and I'm hung up on determining an appropriate search radius.
The default calculation performed by arcgis is to take the shorter dimension ...
- 429
6
votes
4
answers
5k
views
Seeking alternative to ERDAS Imagine? [closed]
I am having trouble with the ArcGIS 10.1 and ERDAS Imagine 9.2 license conflict.
From what I found out it isn't that rare, but I do not understand why there such a conflict in the first place.
...
6
votes
1
answer
2k
views
Does Zonal Statistics value change when applied on subset of data using ArcGIS Spatal Analyst?
I have generated zonal statistics using feature zone data on a value raster. This shapefile contains about 20000 polygons and the analysis went without a hitch.
While testing quality, I ran the same ...
- 388
6
votes
4
answers
2k
views
Find the best path along raster
I've just posted a question to StackOverflow about the best way to go about finding the best path on the raster below (where whiter pixels are 'better'), but have realised that it might actually be ...
- 4,014
6
votes
1
answer
10k
views
Extract raster value to polygon
I am trying to extract raster values within multiple polygons. It would be nice if I could choose between say the maximum or an average raster value within the polygon.
For example, I have created ...
- 203
6
votes
1
answer
3k
views
Raster Calculator making incorrect calculations in ArcGIS Desktop?
I am trying to use raster calculator (ArcMap 10.2.2.3552) to apply a poisson generalized linear model to estimate species abundances based on elevation. The outputs don't make any sense to me, and I'm ...
- 63
6
votes
1
answer
1k
views
How to remove clouds in High resolution Imagery(.5 mGeoeye)
I have imagery with high resolution .5m, large parts covered with clouds, so it's obscure many urban areas.
How can I remove the clouds?
- 1,123
6
votes
4
answers
3k
views
Some zones disappear when running Zonal Statistics as Table in ArcGIS
I'm new to GIS. I want the sum of nighttime lights (DMSP) by district for some country. I'm running this arcpy.gp.ZonalStatisticsAsTable_sa(Limites_distritales, "IDDIST", rc, temp_table, "DATA", "") ...
6
votes
3
answers
2k
views
Using ArcGIS to extend a polygon in one direction up to the edge of another polygon
I have two shapefiles: the first containing a route defined by a single polygon (black line in the image below), the second containing a series of between 1000 and 4000 small polygons located ...
- 181
6
votes
3
answers
2k
views
Clustering neighboring points inside ArcGIS Desktop?
I am using ArcGIS Desktop 10x.
I have a shapefile of 300 points which I need to make groups, each of which will contain exactly 9 points which are closest neighbors.
I tried the 'near' tool, which ...
- 785
6
votes
1
answer
3k
views
Understanding aspect units in QGIS
I created an aspect raster form a DEM raster in QGIS 2.14, and got this results:
I know that the results refer to degree units , but still i don't understand how to read the map result- i mean to ...
- 4,082
6
votes
1
answer
1k
views
Floor height creation from Aerial Lidar/Imagery only
I was wondering if it is possible to generate the floor heights of buildings from aerial lidar? We don't have terrestrial lidar or stereo imagery. I don't need the ground DEM level or the roof (DSM) ...
- 8,298
6
votes
2
answers
2k
views
Solar radiation calculation gives Background processing has encountered serious error and is unable to continue?
I have tried to calculate solar radiation (whole year with monthly interval) for Portugal from an ESRI grid (27m DEM) in Arcgis10. It seems to work, however it takes much more than a week and in the ...
6
votes
1
answer
5k
views
Question about ArcGIS vs. QGIS for kernel density estimations
It appears from the QGIS documentation that the Heatmap Plugin can generate a kernel density surface from a point map and make use of the attributes of the original points to influence this surface ...
- 303
6
votes
2
answers
5k
views
Calculating zonal statistics of raster data in multiple overlapping zones and combining them into one table
The aim here is to calculate the max, min, mean, range, sum, count and std of raster data contained in areas delimited by polygons (much like what the Zonal Statistics as a Table tool from Spatial ...
- 187
6
votes
1
answer
780
views
Error using con in Map Algebra in Python script
I am experiencing a painful problem in the middle of a Python script I am writing. When I get to a Map Algebra function, I have tried two different options and both return a different error.
At first ...
- 497
6
votes
1
answer
5k
views
How should I correctly exaggerate a hillshade raster (ArcGIS10, Spatial Analyst)?
I once wanted to generalize a high resolution raster and instead of MEAN i accidentally selected the default SUM technique, using a cell factor 5 (Lidar DEM is 1m resolution). When I used this result ...
- 20.4k
6
votes
2
answers
17k
views
How to use OR in a CON statement, in the ArcGIS Raster Calculator?
I'm trying to compare two rasters, and create an output based on a formula like:
if raster1 > 10 or raster2 < 20 then raster3 = 30
How can I specify the OR in the raster calculator's CON ...
- 21.3k
6
votes
1
answer
1k
views
Why does tool take longer to run when in Python script?
I have written a python script that does some euclidean allocation. For that I use arcpy.gp.EucAllocation_sa() method. Now, my python script takes 30-40% extra time than spatial analyst euclidean ...
- 2,423
6
votes
2
answers
11k
views
Thiessen Polygon delineation within a Feature
I am trying to create Thiessen (Voronoi) polygons, based on points within a defined shapefile extent.
The output should be inclusive to the feature. The output I receive now is the rectangular area ...
- 128
6
votes
1
answer
996
views
Sum raster data visible from given point, by proportion of view
I am wondering if there is a tool that does the following (preferably in Arc but other options considered).
Simple example: what proportion of the view from a given point on the landscape is occupied ...
- 2,343
6
votes
1
answer
7k
views
Extract Values to Point from Raster Issue
I am trying to use the tool Extract Values to Points on a File Geodatabase raster, but I am getting some weird errors.
I've used this tool multiple times before with no issue, but not since I ...
- 4,387
6
votes
1
answer
7k
views
Watershed Delineation
I am trying to delineate just the catchment area of some lakes, and am wondering the correct way to do this. I already have a filled DEM, along with a flow direction and a flow accumulation raster. Is ...
- 323
6
votes
1
answer
283
views
Extract By Mask gives different result (and WARNING 000622) in ArcPy than from tool dialog?
I'm using ArcMap 10.3.1
When I use the gp tool to extract by mask, I get the correct result with any area outside the mask set as NoData.
When I do the same thing in a script, I end up with cells ...
- 63
6
votes
1
answer
685
views
Determining whether raster pixels in or out of zone
I am running ArcGIS 10.2.2 and often use the Zonal Statistics and Tabulate Area Tools. I wanted to confirm that the area of a pixel will only be included in the tabulated area if the pixel centroid is ...
- 869
6
votes
2
answers
613
views
Increasing search radius of nearest neighbors for Nibble tool?
I am working with a raster map vegetation types. I have about 20 types with unique raster code values that can be sorted into three classes:
vegetation types I want to expand using the nibble ...
- 101