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

learn more… | top users | synonyms

1
vote
0answers
20 views

Curve Number equation

I have a floating point raster of Curve Numbers (70-91) and I'm attempting to use the curve number equation to create a weight raster for flow accumulation, to determine runoff for a single rainfall ...
0
votes
0answers
14 views

Finding regions or zones in raster DEM of similar slope or aspect values in ArcGIS for Desktop?

I have a detailed 5m DEM for my study area. I want to find regions or zones where the slope or aspect (or preferably both) varies little. In other words, a nice evenly sloped hillside with a ...
1
vote
0answers
13 views

Reduce raster resolution and determine pixel inclusion based on % pixel overlap

I'm trying to reduce the resolution of a raster from 1m to 50m using a pixel aggregation (average) method, but I need to set a threshold for inclusion (e.g. 75% of the 1m pixels must fall within the ...
2
votes
0answers
38 views

Draw raster on top of a Leaflet map

I want to implement a raster layer on top of a Leaflet map that includes the following functionalities: Digital Elevation Model (DEM) terrain height included in each raster cell GPS-Track (I use ...
1
vote
2answers
26 views

Issue running r.region in GRASS command line

I'm currently attempting to use r.region to preform analysis on a specific area of a raster image. I'm receiving Lat/Long data from the step before me, but I'm having issues use that data in ...
0
votes
1answer
28 views

Calculating the number of days above freezing in R

Im wondering if anyone has come across any data source that can be used to calculate the number of days where temperatures are greater than 0 degrees C, 10 C and 20 C at a global scale? I have a site ...
3
votes
1answer
60 views

Export raster layer in python to specific folder

I am trying to export existing raster layers as tif files. I just want to avoid saving each raster manually. this is the code I am trying to use, but it doesn't seem to work: from PyQt4.QtCore import ...
1
vote
2answers
28 views

Add raster attribute table to raster using arcpy

I have downloaded US soil raster data by state from https://gdg.sc.egov.usda.gov/GDGOrder.aspx at 10m resolution. I am now trying to add a modified raster attribute table to tif that was exported ...
1
vote
2answers
39 views

Arcpy Reclassify by Standard Deviation

I would need some help with the Reclassify tool. I have written a script that produces rasters which I need to reclassify. My problem is, I want the values to be reclassified by standard deviation ...
1
vote
0answers
15 views

How does “Mosaic to New Raster” tools works? How does it treat pixel values?

I'm working with arcGIS. I have mosaicked 8 rasters with values ranging from -408 to 180. The new mosaic shows pixel values ranging from 0 to 180.Then I compared cell by cell values from the original ...
1
vote
1answer
37 views

Merging and splitting raster files in QGIS

I have four .HGT topography tiles (tile1,tile2,tile3,tile4 in the photo below). They are in geographic coordinate system. I would like to merge those four tiles, and then from that merged raster layer ...
-1
votes
1answer
24 views

Fix AttributeError in python code

I got some code that I think should work, but I'm getting this error: Traceback (most recent call last): File "", line 1, in File "c:/users/proxtr~1/appdata/local/temp/tmpgtrnqo.py", line ...
2
votes
0answers
32 views

QGIS raster style rendering incorrectly/unexpectedly

I have a raster of flow accumulation. To style it, when I set manual values for raster breaks in qgis 2.14 it isn't rendering all values below the value I set in the same colour. My understanding is ...
4
votes
1answer
30 views

Grid size of a Digital Elevation Model developed from topographic surveyed elevation contour line?

I have generated a Digital Elevation Model from elevation contour line. I got these elevation contour line at 20 cm interval from DGPS survey. What would be the grid size of generated DEM in "m". ...
0
votes
1answer
70 views

Save raster layers in a python script

Is there a way to loop through every selected layer in qgis and save it as a .tif file with the same layer name using a python script? This is the code I am using, but it does nothing at all. It runs ...
2
votes
1answer
40 views

Retreive pixel value from raster layer in pyQGIS

I am trying to access the pixel data in all bands from a raster layer in QGis from the Python Console. I have looked at several online resources including ...
0
votes
1answer
27 views

Issues with raster data on postgresql / error:Attempting to get pixel value with out of range raster coordinates

So here is the issue, i am trying to extract values from a big raster divided in 200 or so tiles and applying them to a selection. The points are startpoints, endpoints and midpoints from vector ...
0
votes
1answer
21 views

histogram of raster coordinates in R

I'm trying to generate an histogram of the y coordinates where raster values are 1. Mysteriously the following, different rasters, give me the same histogram. What could I be doing wrong? here are ...
1
vote
0answers
19 views

Map netncf-file with different years and save the different layers in shapefiles

Download from this website the following netncf-file: cru_ts3.23.1991.2000.pet.dat.nc.gz. This is a monthly raster with data from all over the world from january 1991 to december 2000 I am using ...
3
votes
1answer
38 views

How to order QGIS raster layer style?

I have single band raster files that I am trying to style using Singleband pseudocolour under the Layer Properties, Style settings, and a colour map textfile that I upload for styling. When I upload ...
1
vote
0answers
25 views

Clipping raster brick object in R

I have MODIS NDVI TIFF files for a year I want to first clip it with a irregular polygon (not by its extent only) of my study area and save it as a multi band raster in TIFF format The TIFF image are ...
0
votes
1answer
38 views

Cutting raster using ArcGIS for Desktop?

I would like to cut a raster file that I have. Here I attach a example of how it is original: And this is how I would like it would be. (I have cut the image on Paint): Can someone give me a ...
0
votes
0answers
34 views

Cut only a river of a raster file [duplicate]

I have one raster file which has a river that passes in a land. I want to "cut" only the river and save it to another raster file but I do not know how to do it. Can anyone give me any suggestion? ...
1
vote
2answers
46 views

What method does QGIS Merge Rasters tool use?

I am trying to merge rasters in QGIS and want to set a priority order for merging so that the values from the highest priority raster are used in overlap areas (the “FIRST” merge/mosaic method, I ...
1
vote
1answer
24 views

5x5 raster filter in ArcGIS?

Normally, I am using the 3x3 lowpass filter if I need to filter a DEM. However in one case, for better results in curvature calculations, I would like to do a 5x5 filtering. How is this possible in ...
2
votes
1answer
39 views

display historical map without georeferencing?

I have a historical map of Rome that was published as 46 separate sheets. I'd like to scan these sheets, mosaic them together, and display them as a single map. I've tried to georeference a few of the ...
1
vote
0answers
21 views

Adding rasters to mosaic dataset?

I'm working with an ArcSDE geodatabase v 10.0 in SQL Server 2008R2. I added more than a dozen of rasters w/o problem. Server: WIN 2008R2 12GB RAM SPACE: 1TB Created a mosaic dataset (empty) w/o ...
2
votes
1answer
46 views

What is the most efficient way to get a table or attribute table of a float raster?

I'm starting with a stretch point raster. Ultimately I want to get a mean value of values with larger zones and then rate the zonal mean stretching from 0-1 and output rank/zone to a table or layer ...
1
vote
1answer
36 views

PostGIS clipping raster with the same color band as the original raster

I am trying to clip a raster so that the clipped raster would have the same minimum and maximum values for the color band as the original raster. For example if i clip the raster with this command: ...
2
votes
0answers
31 views

QGIS: Merging raster files produces error

I'm trying to merge (Raster -> Miscellanous -> Merge) four raster files into one. Each file has same CRS and are saved as .tif files. Merge produces error: "The process crashed some time after ...
0
votes
0answers
17 views

Add information from a raster nc-file to a polygon shapefile

DATA Download from this website the following ZIP file: NUTS_2006_60M_SH.zip and save all the NUTS_RG_60M_2006 files. In what follows I refer to this as "NUTS3 regions". Download from this website ...
0
votes
1answer
21 views

Combine function on ArcGIS for Desktop?

I am trying to use the combine function on ArcGIS 10.3 for Desktop. I have two raster files that have the same values and I want to combine them in order to compute an accuracy assessment through ...
0
votes
1answer
12 views

Global Raster over GPS Data

i want to build a global raster over all GPS coordinates. The cells should be like 20x20 metres... I want to write an java application and 'work with'/adjust that raster later on. For example to get ...
5
votes
2answers
86 views

Why am I getting two different outputs from Python and C++ using GDAL?

I am trying to gather information from a *.tif file using the GDAL libraries. When I open the *.tif file using both the Python API, and C++ API, I encouter two completely different answers. Here are ...
2
votes
1answer
38 views

What is a raster attribute table?

I've seen raster attribute tables mentioned in several places here at GIS.SE and at ESRI websites. However, I don't understand what is a raster attribute table (RAT). The resources I found so far ...
0
votes
3answers
114 views

ArcPy Script Tool takes 30min - Ideas to accelerate the (raster) process

I developed an arcpy script tool that takes as input multiple rasters, a criterion to select specific cells from the raster which are then intersected with a point shapefile. At the end a value is ...
1
vote
0answers
23 views

Control points in IAdjustXForm for georeferencing of raster (ArcObjects)

I am trying to create a georeferencing tool using ArcObjects in VB.Net. Though only a little text is available on this topic in forums as well as from ESRI; I found an esri article that states the use ...
0
votes
0answers
16 views

Using the extract function in raster package for R with polygons

I have a shape file that contains some polygons and an unprojected raster. I'd like to extract the cells within the polygons using R, so I use code like this: # Load my polygons MyPoly <- ...
3
votes
2answers
60 views

How to generate a buffer outside polygons having a given pixel value?

For example, I would like to build a 20-m buffer (represented in yellow in the image below) outside polygons having a value of 2 (represented in green) and to assign the value of 3 to buffer cells. ...
0
votes
0answers
16 views

Code to sift through many rasters and find rasters with errors using python [duplicate]

I would like a code to go through hundreds of rasters and print the names of the rasters that are problematic/don't work. I am trying to use the in cell statistics however I keep coming up with errors ...
1
vote
1answer
53 views

How can I align perfectly 4 topo sheets?

I have 4 topo sheets and i want then to align perfectly Would I have to georeference each image again? Or is there a more simple method?
0
votes
0answers
32 views

Is it valid to resample a raster from 1m to 3 feet?

I know that in general it is not a good idea to up-sample. I am curious if it would still be be a "bad idea" with a minor change like this from 1m resolution to 3 feet? Going to 3 feet would not ...
1
vote
0answers
19 views

Calculating the distance between points and parts of a underlying raster set

I need your help with a calculation of the distance between points (cities in this case) and forest (raster data). Is there a possibility to collate to every city the distance to the nearest forest ...
1
vote
0answers
17 views

How to unckeck automatically the “No Data Value” predefined on raster background on QGIS 2.14?

I'm trying to import a bunch of rasters, but there is a parameter predefined on the TIFFs, where says that No Data Value should be marked. But I need this unchecked. I opened the metadata, and found ...
2
votes
1answer
21 views

QGIS raster no data value changed to -inf when viewing at smaller scale

I have a raster with some no-data cells. I want to visualise raster values using a colour map and set the no data values to transparent. I am attempting to do this using the transparency tab in the ...
0
votes
3answers
69 views

Extracting impervious areas (buildings, rails, pavements) from LAS dataset [on hold]

How to extract impervious areas (like buildings, rails, pavements etc.) from las dataset and receive it like a raster? I tried to do it with intensity, but there are many valids with vegetation. I ...
0
votes
1answer
26 views

Error message received when cropping raster with clipper

QGIS 2.10.1 Pisa Message -> Error: Computed -srcwin 8208 142185 0 0 has negative width and/or height. Tried with several different files and types of raster files [GeoTIFF, MrSis, ECW], the same ...
0
votes
2answers
35 views

How to Call ArcHydro Tools in Stand Alone Python Script

I am currently using ArcGIS ArcHydro tools to perform 'Catchment Polygon Processing'. However, it is proving time consuming to perform this for multiple rasters. How might a write a python script to ...
2
votes
1answer
69 views

Finding problematic rasters in large set of rasters using ArcPy?

Just wondering if anyone knows how to quickly find rasters that cause errors when I attempt to process them in cell statistics (as I am trying to sum them). I have many hundreds of rasters and don't ...
1
vote
1answer
50 views

Find NoData values inside a polygon area from a raster

I have a raster (representing a polygon in black) which contains NA values (represented by white pixels) that are located inside the polygon and outside the polygon. How can I get the index value ...