Tagged Questions

Rasters are regular grids of values, usually stored in an image-like format.

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2
votes
1answer
13 views

Clipping a raster in R

I am building a map for the northeastern U.S.A. The map background needs to be either an altitude map or a mean annual temperature map. I have two rasters from Worldclim.org which give me these ...
0
votes
1answer
25 views

value field name after raster to polygon conversion

When I perform Raster to polygon conversion using tool, sometimes it creates a field named "GRIDCODE", sometimes the field name is "grid_code". Why does it create random name of a field?
1
vote
1answer
24 views

Raster to polygon conversion's raster field takes only “Value”

Recently I am working with raster data and arcobjects.net. Here I find something new for me. And here some question arises in my mind. I tried to search some document that can satisfy my mind, but I ...
0
votes
1answer
38 views

Field added to raster data is not visible in attribute table

I am new to raster data and my background is software engineering so this might be a trivial question for GIS specialists. Some raster files have attribute table but some do not. On those with ...
3
votes
3answers
60 views

Can a single raster pixel hold more than one value?

I am a newbie with raster data. Maybe this is a trivial question. Can a single pixel of a raster hold more than one value?
0
votes
0answers
14 views

Loading raster from PostGIS DB into QGIS: succeeded yesterday, fails now

I have a PostgreSQL(v.9.2)/Postgis(v.2.0.3) database which includes raster layers (added through raster2pgsql). To open them in QGIS (v.1.8.0-Lisboa), the "Add Postgis layer" menu will not work; ...
0
votes
1answer
33 views

Can ArcPy collapse layer in current data frame?

Online arcgis resource help provides a list of layer properties which can be used as needed. I am not able to find a way to collapse a layer using arcpy in it. Please suggest if there is a way to ...
1
vote
3answers
60 views

How can I reclassify a raster to floating point values?

I have a raster of landuse values that I need to reclassify into pollution concentration values. I have the pollution values in a separate table. They are decimal values (ex. 0.0056), and my landuse ...
1
vote
1answer
23 views

Why does the Zonal Statistics tool always return 0?

I have a slope raster created from a DEM raster with the DEM Analysis tool. Now, I would like to calculate the average slope in a given area represented by a vector polygon layer. I thought I could ...
-1
votes
0answers
22 views

Generate files TFW from a text listings [closed]

I have a list with all dat that must have any tfw files. Anyone know if there is some tool to do this automatically.
0
votes
0answers
34 views

How can i calculate the width of the dam?

I am working with Reservoir design. Now I am facing problem to calculate the width of the dam. I need to calculate the width based on DEM and height of dam at various points using Python. I am working ...
0
votes
0answers
22 views

GDAL: add metadata to Bands when creating new GeoTIFF

This is a metadata question :-). I am processing airborne laser scanning full-waveform data to extract information and I store this information by creating a multiband GeoTIFF using GDAL. I will have ...
1
vote
1answer
44 views

Problem with calculating the total cell values

aa= arcpy.RasterToNumPyArray("water_depth") sum = numpy.sum(aa) print sum -2933737 Why I am getting negative values ? In my raster there is no any negative ...
2
votes
1answer
42 views

Tabulate Area crashes Python and ArcGIS

I have a script that runs Tabulate Area on a single feature class multiple times with different rasters. In total Tabulate Area runs 5 times. 2 of the input rasters are provided as arguments to the ...
2
votes
1answer
43 views

Raster Version of Spatial Join (one to many) [duplicate]

I have two raster layers that are identical in shape (they overlap exactly) and I need to perform the raster equivalent of a Spatial Join (one to many). My files need to stay in raster format ...
1
vote
0answers
25 views

Different results from Spatial Analyst GP Tool and Python

I am writing a script that has to subtract one raster from another. The rasters I have represent 1) Parking Lots (1 = Parking Lot, 0 = not Parking Lot) and 2) a buffer around the Parking Lot (1 = ...
1
vote
0answers
18 views

QGis Grid statistics for polygons error - Module caused access violation!

I'm trying to calculate statistics for a raster layer using an overlaying polygon layer, I'm using SAGA "Grid Statistics for polygons" function, but it returns an error, sadly.. So in the sextante log ...
4
votes
1answer
53 views

Raster to vector with gaps in Landsat ETM

I need to find size of water area from a raster (jpg) using QGIS 1.8.0-Lisboa. The raster is a Landsat image with gaps of data in it. I used Polygonize, but the output file shows wrong polygon size ...
0
votes
1answer
22 views

Add a time dimension in ESRI mosaic raster dataset

I am in the process of creating a script to pull daily .asc files from a ftp server, convert them to a raster format, and push them into a mosaic raster dataset. Ultimately, the raster dataset will be ...
-2
votes
0answers
18 views

ArcGIS 10.1 Data Driven Pages Raster Rendering from Current extent

Data Driven Pages are not honoring the Raster Rendering by current extent when exporting multiple pages to pdf. The current map page works fine, but subsequent pages use the same color rendering (ie ...
0
votes
1answer
21 views

Extraction of raster cell values based on 'rgeos' and 'raster' buffering approaches in R

I am trying to extract cell values from a raster that lie within a certain distance from a given location (i.e. buffering). Evaluating different approaches, I found out that applying gBuffer(..., ...
1
vote
0answers
19 views

How to combine two rasters, preferring the values of one over the other? [duplicate]

I have two rasters that I need to combine (not using the Combine tool). The values of the 1st raster are preferred to those of the 2nd raster, so I want to keep these values if they exist. Where the ...
1
vote
1answer
29 views

Calculating Volume of Reservoir using python and ArcMap10? [duplicate]

I have a raster file with different water depth in each cell. I am using Aster DEM so my resolution of that file is 30m by 30m. Now I want to calculate the total volume in that area by multiplying ...
0
votes
0answers
21 views

Sum all cells in raster using javascript

I'm creating an agent-based model in Agent Analyst for ArcGIS and I need to sum all the values in a raster that has about 7 million pixels. I'm a very beginner in programming, and have a script that ...
3
votes
1answer
38 views

Is it possible to batch clip rasters in Quantum GIS?

I have been able to batch clip rasters in one directory using python in ArcGIS. However, I am not sure how to do the same in Quantum using the python console. Is this possible? If there are different ...
0
votes
0answers
15 views

GDAL Utilties - Multiple Bands with Different Output Types

I have a raster dataset with 5 bands. 4 of the bands are 8bit unsigned and the 5th band is 32bit floating point. I need to clip the dataset into tiles using GDAL (I'm using gdalwarp with a cutline ...
0
votes
0answers
25 views

Explaining the output from ArcGIS' Principal Components tool

I have completed the process but am unsure whether I am interpreting the output like I should, particularly the text file. I am especially interested in the "EIGENVALUES AND EIGENVECTORS" portion.
0
votes
0answers
26 views

Raster attribute field error [duplicate]

I am trying to add jpegs to a raster data type attribute field. I want to this field to be managed by the file geodatabase. When I load the photos and try to save my edits it get various errors but ...
5
votes
2answers
92 views

Creating randomly shaped clumps of cells in a raster from seeds of 1 cell/pixel?

As my title says, I wish to "grow" clumps of cells from seeds within a raster. My base raster is full of 1's and 0's, 1's indicate land and 0's sea/NA areas. From the 1's I wish to select 60 random ...
4
votes
2answers
56 views

How to extract values from rasters at location of points in R?

My question is about extracting values from rasters at the location of points. With the function extract this is very easy, and the function gives me a dataframe with the values of all the variables ...
2
votes
1answer
46 views

Web mapping application with time slider and raster data

I need to create a web mapping application that can show raster layer of historical maps with a time slider. Basically, something like this: http://goo.gl/GYHOX I have different maps of different ...
1
vote
2answers
44 views

Create Raster file in R from Matrix and latlons

I could use some advice on how to create a Raster file in R with a Matrix of datapoints and the coordinates stored in a seperate file. Both, data and coordinates come from a NetCDF file. I extracted ...
0
votes
1answer
23 views

how to create a new raster from one field of a raster with several fields in a RAT

I have a raster with an attribute table containing many fields. I want to create a new raster from one field using arcGIS 10.1.
1
vote
0answers
52 views

How to get Lon/Lat values from the postgis raster type column

I have a tiff raster in my PostGIS 2.0 database. I want to get the value lat/lon and extra data like temperature from the raster type column in postgis table. I want the table with columns ...
0
votes
0answers
16 views

Get Complete Details Of Raster Column in the Raster Table

i'm having the geotiff files containing the details of the temperature of the specific co-ordinate value along with it. Configuration details: Postgresql 9.2, Postgis 2.0, GDAL 1.9.2. Here my ...
2
votes
1answer
28 views

Raster Tile Merge Performance of PostGIS 2.0

I'm attempting to intersect Australian Census boundary polygons with the 1" SRTM DEM (10.5bn points across Australia), and output the result as a single raster image on the fly. The DEM is stored in ...
6
votes
3answers
109 views

How to efficiently read and reclassify many rasters in R

I've been tasked to create a suitability analysis of wave conditions in the Gulf of Mexico. I have 2 thousand or so raster files that are about 8 MB each (2438 columns, 1749 rows, 1km cell size). ...
2
votes
0answers
44 views

Problem in importing raster data from PostGIS to Geoserver

I am using Opengeo Suite 3.0.2, PostGIS 2.0.3 and PostgreSQl 9.2. I am trying to import raster data from PostGIS to Geoserver but facing an error. I follow this tutorial link to import the raster ...
0
votes
1answer
40 views

How do I combine many ECW files in MapInfo?

I have MapInfo 11.5.0.16 (I don't have ArcGIS) and I am trying to combine (in some sense) a large collection of ECW files. I can load one ECW at a time in MapInfo but I have very many. MapInfo ...
2
votes
1answer
87 views

How to calculate volume from a raster file?

I have a raster file containing the depth of water. I need to find the volume of water using that raster file. I need to find the area of each cell and multiply with the depth. How can I do it in ...
3
votes
2answers
65 views

How to calculate the shared area between a raster and a shape file in ArcGIS 10?

I have a raster file with 5 classifications developed from habitat modelling algorithms. I'd like to know how much of 2 classes of the raster is covered by the network of protected areas (Shape file). ...
1
vote
0answers
37 views

Feature to Raster Conversion Results in Empty Raster [closed]

I have a simple shapefile with one feature in it with a single value (of 1). I am trying to run a Euclidean Distance on that feature, but I get "invalid parameters" errors. So I tried to convert the ...
0
votes
2answers
68 views

How to delete isolated pixels in ArcGIS 10.1?

I want to know that it is possible or not to edit the raster pixel in ArcGIS. I want to delete isolated pixel and I want to delete some pixel by manually. please tell me how can i do it manually or ...
0
votes
0answers
17 views

Can I apply the Euclidean Distance tool for a single point feature class? [duplicate]

So, as suggested in my previous question, I tried to perform perform the Euclidean Distance tool for a single point feature class. For som e reason it doesn't work and the error given is ERROR010092: ...
2
votes
1answer
48 views

Create raster distance around a single point feature class

Okay, so I'm relatively new to ArcMap and I'm trying to use the Fuzzy membership for suitability test. I have a single point feature class that I wanna use for this analysis. I know that in order to ...
1
vote
1answer
55 views

No. of Bands in the input Raster

I have downloaded a 7.5 min DEM . Now while I am trying to mosaic them it gives me an error saying "Input and target dataset should have the same number of bands" . How can I figure out the number of ...
2
votes
2answers
46 views

Raster format to read with python

I currently have a DEM raster stored in an ESRI geodatabase. I've been asked to create a purely python (e.g., no arcpy functions) program that works with the values. Therefore, I need to convert the ...
1
vote
0answers
55 views

QGIS: Different projection result for on the fly and transformation

I am a bit confused about the result of a re-projection/transformation of a raster in QGIS 1.8 (Lisboa). WGS84 to WGS84/UTM34N. When I use the 'on the fly' transformation the resulting raster has a ...
0
votes
1answer
34 views

Maintain 8-bit pixel depth in Raster Calculator

Would anyone know how to maintain 8-bit pixels when computing raster calculations in ArcMap?
1
vote
2answers
44 views

Calc vs. Overlay for speeding up band math in R 'raster' package?

Regarding yesterday's question about how to speed up band math in the R 'raster' package, would it be the same to use overlay to calculate NDVI instead of calc? If that's not the case, what's the ...

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