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

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Raster statistics for polygon areas PostGIS

I'm trying to get zonal raster statistics for each polygon area. I have used the following method from this site: SELECT bufid, (ST_SummaryStatsAgg(ST_Clip(rast, geom, true))).* FROM rasttable, ...
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19 views

Calculate the frequency of classes of neighbouring raster cells

I'm struggling with a problem when working with a raster dataset of biotope types: For each cell I would like to find out the frequency of classes in the adjacent cells, e.g. from the 8 neighbouring ...
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55 views

Why does an 32-bit FGDB raster have a smaller file size than 8-bit?

Using Arc 10.0, I have a single band, 32-bit signed raster as the only item in a file geodatabase. Using ArcCatalog, I copy that raster to a new geodatabase with an 8-bit unsigned pixel type. As ...
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157 views

How to speed up this script in QGIS?

I am a new in PyQGIS, I want to create a Point layer from a raster layer. In table of point layer created, there is 3 fields by name of "X_coord", "Y_coord" and "Azimuth", each point in Point layer ...
3
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1answer
32 views

How to combine 2 vector shapes created from raster files

In Qgis 2.12 Lyon, using windows 10 I downloaded 2 raster files from an area of my interest. The rasters were on information about precipitation and evapotranspiration. Each cell had a value. I ...
4
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1answer
59 views

GRASS GIS temporal raster individual layer statistical summary

I have created a temporal raster in GRASS GIS which has 90 layers. I would like to extract the mean of each raster layer and export it as text file. Right now I have to export the rasters as GeoTiffs ...
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31 views

QGIS polygonize tool not working [closed]

I am having a problem using QGIS ver 2.10.1 Pisa. I am trying to use the polygonize function on a raster .tif image, and it runs, but only produces a thin sliver of polygons at the top, then stops ...
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8 views

Created raster with not expected range

I have created a raster layer with kriging tool as source of data have localized sapefile attached and shown in Figure. Why the value range and are produced raster information is irrelevant to the ...
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205 views

Make several rasters more uniform

I have imported some rasters that is supposed to be continuously connected but instead they create some sort of bordered grid between them. I may assume that this is a matter of calibration between ...
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1answer
52 views

Change NODATA values to 0 in Qgis

I know this question has been asked already in this forum, but I couldn't find an easy (for me, a rookie) solution for my problem. I have an RGB 3 band file which, in some pixels, has i.e. R no data ...
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0answers
17 views

how to generate a raster with its spatial reference from an array(or matrix) by using pyqgis

I used arcgis to generate rasters from txt files by a certain python api,but i am not familiar with qgis,and now i need generate some rasters from txt files by using pyqgis.The resulting rasters ...
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24 views

How do I create a raster file from a geopandas dataframe storing lats, longs, values, and geometries

From a text file with time, lat, long, and cf values, I create a pandas dataframe (cf_df). Then I use the lat, long values to create a geoseries and create a geopandas dataframe from the original ...
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13 views

Export RAT (KEA driver) to Shapefile

I have a dataset of rasters (driver kea) whose has, let's say, 20-30 attributes in their RAT. I'm realizing how to have these attributes in shapefiles (without using proprietary software). I've read a ...
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35 views

R Efficient Way to Resample, Crop, and Mask a Raster Image

Does anyone know an efficient way to resample an image? I am currently trying to crop a large image and clip 2 regions from a shape file. From this clipped image, I would like to increase the pixel ...
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1answer
31 views

Area estimation using raster image

I have a map of trace gas (NO2) distribution over big cities and other anthropogenic objects. The purpose is to estimate the area of distribution. I attached the sample image to illustrate what I do. ...
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1answer
39 views

Reprojecting and retiling a large set of tiles

I am trying to understand the process to re-project and re-tile a set of raster (GeoTiff) but can't wrap my head around how to use the different GDAL tools to achieve my goal. More concretely, I ...
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31 views

Get distances between boundaries from an SpatialPolygon and raster pixels

I am trying to calculate the distance from several pixels of a raster to a boundary of some polygons in R as it is showed in the image. I have two problems: How to correctly define a boundary from ...
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2answers
37 views

R calculate raster cell size in map units

I have a RasterLayer and would like to know the cell size. I haven't find any function in the packages :-S . Does someone have an idea ? info about the RasterLayer class : RasterLayer ...
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1answer
32 views

Exporting a raster with renderer enabled to file

I have a problem when trying to export a layer with renderer to a file. Basically, what I have at start is a correct IRasterDataset. Then I define a stretch renderer in form of IMultiPortColorRamp and ...
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1answer
39 views

Raster Layer Statistics CSV Output using QGIS Graphic Modeller

I am currently working on a project where I am using historical cloud coverage from MODIS Cloud Fraction data to try and estimate future cloud coverage of any particular month. I currently have ...
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0answers
17 views

Access MEM data from GDAL?

I don't have any answers (yet) from from previous question on GDAL memory raster + OpenLayers, so i'll try to ask an easier question :) Anyone knows how to access GDAL memory with command lines when ...
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17 views

Raster colormap setting in Arcmap not honored in GP tool

I am working with digital versions of paper maps. Here is what I am attempting to do: In Arcmap determine the value in a raster's colormap that is the undesired black mask / "no data" section. Set ...
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1answer
18 views

My raster does not line up with rest of vector shapefiles, even though both rely on NAD 83

I started creating a map in ArcMap by adding vector shapefiles. All of my vectors have data sources as: Data Type: Shapefile Feature Class Geometry Type: Line Projected Coordinate System: ...
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1answer
26 views

Defining the correct AEA proj4string for FEWSnet Rainfall Data (Southern Africa) in R [closed]

I have some general questions about how to go about solving this problem: I am trying to incorporate FEWSnet's monthly Rainfall Estimate data from 2014-2015 for Southern Africa into an analysis where ...
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2answers
40 views

R: aggregate raster with 'mode' function - how does it work?

I want to aggregate a very fine resolution raster at various coarser resolutions (that represents many 1000s of categorical polygons). The aggregate{raster} function is what i've traditionally used, ...
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1answer
28 views

Why doesn't Ordnance Survey street view raster layer appear on qgis map?

I've downloaded the relevant 100 km square of OS Street View raster data and have added the relevant 5 km square to a QGIS 2.8.2 map of scale 1:1500. The layer can be seen in the layers menu but not ...
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2answers
36 views

What is the SRID of LCC projection?

I have a raster file with LCC projection and a point dataset with SRID 4326. I want to extract raster value to point. When I use the query SELECT ST_Value(rast, geom) val FROM testraster5, ...
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6 views

mapnik.Gdal(file=my_latlon_raster_file_path) returns a datasource with an empty all_features() list

When I get my mapnik layer datasource like that for a raster file: layer = mapnik.Layer(my_raster_layer_name) layer.srs = my_srs layer.datasource = mapnik.Gdal(file=full_path_to_my_raster_file) and ...
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32 views

Extracting Mean from Raster and Writing to Table in ArcPy?

I am simply trying to extract the mean of each raster within a geodatabase and write the value to a table. I have done this successfully with another set of rasters, but now I keep getting the ...
0
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1answer
24 views

Masking low quality raster with polygons in R gives weird overhang?

I am pretty new to R, and have been attempting to use the mask function on a raster image of 250mx250m resolution. My problem is that for some reason I am getting overhang, as there are pixels which ...
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28 views

How to generalize a raster with noisy edges with ArcGIS Desktop?

I'm trying to generalize a raster to get clean edges (see sample and "optimal" result below). However the borders bleed into each other to a rather high degree. I hacked away at the raster using ...
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16 views

Choosing pixel size when projecting raster from geographic to projected coordinate system

I have a raster showing animal abundance in all of Canada. The raster was created unprojected in GRS 80 with a pixel size of 0.0833 decimal degrees. I was ask to project this raster to Canada Albers ...
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23 views

Polygon to Raster tool while keeping less than maximum values

I'm trying to convert a very large, detailed polygon to a raster with a coarser resolution in ArcGIS 10.1 using the polygon to raster tool. The value field is a percentage and the cellsize must be the ...
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0answers
22 views

St_intersects returning false results in postgis

I want to intersect point geometry with raster. In postgis I'm executing select st_intersects(geom,rast) from testraster1,pft_pft and the result is false even though the points are sitting on ...
2
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1answer
40 views

Automated clearing /tmp using QGIS batch processing?

I'm currently batch processing a bunch (~200 x 200MB) of ascii grid surfaces using some SAGA and GDAL algorithms in QGIS and have been running into "out of storage" errors. The issue is that between ...
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1answer
30 views

extracting statistics from a raster within the extent of a polygon

I have a polygon representing the extent of a study area. This polygon is overlaid to a raster representing the quality of land, which is classified into 5 classes (from bad [1] to good [5]). I would ...
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1answer
20 views

Error trying to call for raster file in gdb RasterToPolygon [closed]

I'm trying to convert raster to polygon. But I'm running into error. ERROR 000865: Input raster: C:/Juivy//python/python.gdb/test does not exist.. This is what I wrote: import arcpy workspace = ...
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1answer
44 views

Why is raster data in range 0-255 in PostGIS?

I'm having trouble interpreting some data I've loaded into a PostGIS database. I scraped rasters from here and converted to sql files using raster2pgsql. I'm now using PostGIS's special functions to ...
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2answers
31 views

How to create for each point feature an Euclidian Distance raster in ArcGIS

I need some comment on how to create an Euclidian distance raster for a point dataset of about 100 features in ArcGIS. I need to create a raster for each single point. My question is, if there is a ...
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0answers
13 views

“Problem loading output layers” error when running algorithms on rasters in QGIS

I am trying to delineate a catchment from SRTM 1arc second data in QGIS. For this, I first try to use the Fill Sinks algorithm and then the Catchment Area algorithm. Both of the operations gives a ...
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1answer
54 views

How does Resampling raster work at corner cells?

This may seem quite a simple question for which I couldn't find a satisfactory answer. I have been trying to understand how resampling of raster work with ArcGIS 10.3, in both cases of refining and ...
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1answer
39 views

Performing raster calculations with more than two bands in PostGIS?

We need to perform raster calculations using more than two bands in PostGIS. At the moment, ST_MapAlgebra has a two-band form but doesn't support more than that. I'm open to any solution others ...
0
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1answer
34 views

compare three rasters and three conditions with overlay in r

I'm trying to run an overlay function with rasters where I want to meet all of 3 different conditions at each cell and produce a single raster as output. Running ifelse with the & operator ...
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28 views

Same CRS but different units of raster cells in qgis

I have two rasters with the same CRS (WGS 84/UTM 34N). One is from a LiDAR scan and the other raster is created thru interpolation of point measurements by me. I would like to change the cell size to ...
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1answer
23 views

output raster size in zonal statistics [closed]

Using zonal statistics, my input raster is 1*1 and input value raster is 10*10. I was hoping the output raster will be 1*1 but it is 10*10. What is the error here ?
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How to use a raster dataset to store and retrieve “vectors” using Python?

For a rectangular area of about 10 by 10 km, I have to generate "displacement vectors" with a 1 meter resolution (i.e. a delta-x and delta-y value for every cell of 1 by 1 meter). I will end up with ...
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2answers
47 views

Least Cost Path Distance to nearest polygon

I have multiple polygons (destinations) and an elevation raster. For each raster cell in my study area, I need to calculate the distance to the nearest destination polygon. If I use the 'as crow ...
3
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1answer
46 views

Calculating proportion of polygon by value in QGIS?

Using QGIS, I have a single-band raster with with multiple counties. I have reclassified the pixels into 2 categories, using a singleband pseudocolor, based on their value ( > or < 3800), ...
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25 views

Stretch to MinMax results in blank render output in QGIS?

I am a new QGIS user, and I can't figure out if I encountered a bug. If I have a multi-layer image, and "Multiband color" -> "Stretch to MinMax" selected I get the following behaviour. QGIS takes a ...
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1answer
33 views

Processing time/speed for Mosaic to New Raster

I have a question on speeding up “Mosaic to New Raster” or finding an alternative. After completing a suitability analysis we are trying to define movement corridors. We used a modified CircuitScape ...