Raster is a data format consisting of regular grids of values, usually stored in an image-like format.

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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?
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210 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 ...
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974 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 ...
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3answers
120 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?
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2k views

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

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; ...
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2k 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 ...
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2answers
590 views

How to generate TFW files for a list of images?

I have a few digital images that are not georeferenced. E.g.: Img01.tif Img02.tif ... Img99.tif On the other hand, I have a text file, which contains georeferencing information for these ...
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30 views

Assign value to raster cells within masked area [duplicate]

The answer I previously received for this question did not solve my problem...please keep in mind that I am a GIS beginner, and it's quite likely that I carried out the proposed solution (using ...
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1answer
307 views

How to read XY, get raster value and then update field?

I've written a script to run through a point layer, using the SearchCursor in the data access module and then read the XY values. Within the with statement, I then use GetCellValue to get the ...
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1answer
187 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 ...
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2answers
325 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
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1answer
2k 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 ...
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164 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 = ...
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445 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 ...
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1answer
314 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 ...
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2answers
429 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 ...
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410 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(..., ...
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34 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 ...
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1answer
143 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 ...
3
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1answer
600 views

Why is Orthorectify button not active in Image Analysis Windows in ArcGIS10?

I wanted to Ortho rectify GeoEye HR imagery using existing RPC and IFSAR DTM in Image Analysis. According to ArcGIS Resource center ...
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3answers
1k 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 ...
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29 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 ...
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648 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 ...
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2answers
3k 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 ...
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1answer
642 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 ...
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2answers
344 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 data points and the coordinates stored in a separate file. Both, data and coordinates come from a NetCDF file. I extracted ...
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251 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.
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444 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 ...
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1answer
351 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 ...
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3answers
3k 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
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1answer
744 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 ...
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869 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 ...
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1answer
1k 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 ...
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2answers
466 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). ...
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2k 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 ...
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1answer
708 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 want to use for this analysis. I know that in order to ...
2
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1answer
4k 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 ...
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2answers
91 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 ...
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71 views

Maintain 8-bit pixel depth in Raster Calculator [duplicate]

Would anyone know how to maintain 8-bit pixels when computing raster calculations in ArcMap? This is part of a model so I need to keep the image with the original 8 bit, do the calculations, convert ...
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2answers
438 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 ...
3
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1answer
332 views

Visualizing Spatial Query

I'm new to GIS applications and trying to figure out what options I have for visualizing spatial query results that combine raster and vector data using OpenLayers/GeoExt/GeoServer/PostGIS. A ...
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58 views

Problem with Georeferencer not scaling TIFcorrectly

I am trying to use QGIS and the Georeferencer to digitize paper maps but I am unable to get the raster to rotate afte I pick my control points. Below is a brief outline of the steps I used to ...
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31 views

QGIS: Unable to project raster layers correctly on a Toshiba Tecra 64# Win7

I know how to project a raster, I can do it on other machines. On this particular machine the raster loads but are no where near the correct position as if the datum is on another planet.
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1answer
472 views

GetCapabilities Request for WMS

I'm trying to connect to a WebMapServer with the Geotools WMS classes. My problem is, that the resonse-object "capabilities" doesn't contain all layers. When I'm doing the request in a browser, I can ...
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151 views

How to find locations for hydro power using raster analysis?

I have a stream network and DEM file both in raster format. I need to extract values from DEM to stream network. For the analysis in stream network after that, I need to find out the places for hydro ...
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198 views

ImageMosaic-JDBC Error

I'm trying to get postgis raster layers in geoserver-2.3.1, with postgresql-8.4, postgis-2.0 and gt-imagemosaic-jdbc-9.1.jar support. I'm going through the tutorial with a PNG raster that i have. In ...
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3answers
668 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. ...
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2answers
790 views

Resample, ArcGIS: How do I avoid resample taking into acount NoData values?

I am trying to Resample a raster dataset to match the resolution of another dataset. I have fine resolution data on small islands (surrounded by NoData in the sea). When I re-sample the data to a ...
3
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1answer
423 views

How to speed up band math in R 'raster' package?

I have some GeoTiff rasters with over 100 bands in total, but they are not huge: resolution is about 1200x600 and total size is less than 7 mb. I'm trying to do a simple NDVI calculation: raster ...
9
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3answers
652 views

How to extract breaklines from a given DEM?

Breaklines are very useful for describing a terrain - for example to build an exact TIN. My question is, how to extract these breaklines from a given DEM? I calculated the curvature (vertical) - ...