Questions tagged [postgis-raster]

PostGIS Raster is a PostGIS data type for storing and analyzing raster data.

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Different pixel values for a raster between QGIS and PostGIS

I have inserted a Landsat raster into PostGIS using the command : raster2pgsql -I -C -s 28356 -M -t 100x100 /data/LS7_20150425_B40.tif public.red | psql -d postgres -U postgres Using QGIS, I have ...
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1answer
371 views

PostGIS Raster performances

I ingested two Landsat images into PostGIS database using : raster2pgsql -I -C -s 28356 -M -t 100x100 LS7_20150425_B40.tif public.red | psql -d postgres -U postgres raster2pgsql -I -C -s 28356 -M -t ...
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1answer
378 views

Using raster2pgsql to display data in QGIS

I am quite new to this process (using raster data in PostGIS) and tried to find some tips/solutions on other threads but I didn't manage to get things working. I ingested some Landsat data into my ...
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1answer
221 views

Display simple raster file in openlayers

I have raster files (one sample can download from here) just have values for points and in beside i have top-left and bottom-right geo data and pixel size of file. so i want to just simply display ...
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0answers
128 views

Add bands or new raster column in Postgis?

Would it be faster to work with a new band or a new raster column for a raster dataset in Postgres with new pixel values, assuming that the size, extent and everything else relevant remains constant? ...
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305 views

How to perform spatial interpolation using PostGIS? [closed]

I need to interpolate some point data and would like to use the ST_InvDistWeight4ma function. As I am new to raster PostGIS, I would like to get some help about this.
6
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1answer
1k views

Converting a PostGIS raster back to vector

Is it possible to convert a PostGIS raster back to a line? I'd like to generalize some vector data by converting it to raster and altering the cellsize to fix 'gaps' in the vector connectivity. Once ...
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0answers
651 views

How raster files are stored in databases? [closed]

When storing raster files in PostgreSQL only one row is created in the database, but the raster is a matrix so typically it must create rows and columns. I want to understand how raster files are ...
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2answers
319 views

How to classify a raster using QGIS Plugin interacting with PostGIS?

I'm developing a QGIS plugin where users can enter some parameters (like distance, depth, area...) and by submiting the plugin interact with a PostGIS database and extract informations form vector and ...
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1answer
448 views

St_Difference between raster and vector using PostGIS

I want to calculate the difference between a raster and vector layer, I used this querie but it's so slow and I don't know if it's right or not. I'm not using st_difference because it only support ...
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3answers
7k views

Poor performance with storing large rasters in PostGIS and visualising in QGIS

my question concerns the use and performance of several software tools in conjunction, namely PostgreSQL, PostGIS, QGIS, and GDAL. I'm a long-time ArcGIS, Python, and R user who is interested in ...
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1answer
383 views

How to perform slope using PostGIS?

I want to perform Slope using PostGIS. I used this query but I got a strange result unit: create table my_slope as SELECT ST_Slope(rast,1,'32BF','PERCENT',1, false) as slope FROM my_raster I wonder ...
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1answer
621 views

Selecting all pixels above a given value in a raster in PostGIS

I have a raster with one band whose value represents the date of the occurrence (a sequential integer). This raster file gets updated regularly, and each time that happens, I need to run a process ...
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2answers
300 views

Is it possible to georeference raster stored in Postgis?

I'm looking to store a huge raster aerial image (400 Gb) into Postgis, but before storing it i like to know how i could georeference or rectify raster stored in postgis ? is there any Qgis plugins ...
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1answer
2k views

How to view a postgis raster query in QGIS

I have successfully loaded a large number of .asc images (>2800 200x200 tiles) into a Postgres table with PostGIS 2.1 support. The new table appears in QGIS's DB Manager and I can add the whole image ...
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0answers
361 views

I am getting error in PostGIS 'function st_clip(raster, integer, geometry) does not exist'? [closed]

I have to find the count of the number of pixels in a given band of a clipped raster. For clipping, I am using ST_clip(). Through clip function raster is clipped with a polygon. I am getting ...
2
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1answer
646 views

How to get pixel values/cell values for stored raster files in postgis?

Raster files in tiff format are storing into database.However I gets only an attribute table. Is there any way to retrieve pixel values/cell values in the table. I have used raster2pgsql command for ...
2
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1answer
551 views

Create a raster with fixed 10meter pixel scale in PostGIS

I have a series of points that I would like to convert to a raster, and then calculate the area of the raster as a proxy for "amount of area covered". I'm trying to do this using PostGIS rather than ...
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160 views

Is there PostGIS equivalent to arcpy.sa.Slice() function?

I have an existing system built on an 8.3 PostgreSQL database which uses a ArcGIS - Spatial Analyst for a couple of raster operations. The system is moving to PostgreSQL 9.2 and I'm evaluating if the ...
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1answer
97 views

Is the PostGIS Raster primary key required to be named rid?

In all examples from the PostGIS Raster reference the primary key in tables with a raster column is named rid. I wonder if that naming is expected by any functionality of PostGIS itself or any client ...
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1answer
435 views

Can I make tiles of a raster in postgis?

I am doing some work on dtms in postgis. To import the dtm, I snipped it into tiles and the work directly on the dtm works fine. Then I calculated aspect and slope of the dtm and got some bad ...
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2answers
610 views

Is there an open standard for raster information?

For geographic vector data (Features) there is an OGC standard that defines geometries and their different annotations such as WKT and WKB. For raster image data however, I was not able to find ...
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2answers
3k views

Downloading raster data into python from postgis using psycopg2

I have raster data in a postgres table that I want to get into python as a numpy array. I am using psycopg2 to connect to the db. I am able to download the data but it comes back as a string (probably ...
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1answer
2k views

Importing GeoTIFF into PostGIS without raster2pgsql?

I know that one can import GeoTIFF into PostGIS via raster2pgsql. I was wondering if there is any easy way (as a sequence of SQL statements) to do the same without resorting to the command line tool? ...
3
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1answer
698 views

Replacing pixel value by lookup table using PostGIS?

I was wondering if it is possible to write a PostgreSQL statement to replace the value of each pixel in an input PostGIS-raster with a value obtained from a look up table. For example, suppose I have ...
3
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1answer
516 views

How to speed up raster/map algebra in PostGIS?

I am testing map algebra with PostGIS (2.1 with PostgreSQL 9.3) on two images, and found it to be rather slow. For example, dividing two images of 7200 * 3600 pixels took 110 ~ 120s on a desktop with ...
13
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1answer
426 views

PostGIS raster summation (map algebra)

I have a table of polygons representing travel time isochrones on particular days. For each origin point, there are five isochrone geometries (stored in separate rows). For each origin point, I want ...
4
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1answer
465 views

postgis resampling two rasters to a common grid system?

I am testing the PostGIS map algebra (ST_MapAlgebra) on two different raster tables. Each table contains a single image/row. They have the same SRID but different, overlapping extents and different ...
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1k views

Uploading raster format(*.tif) to postgis through raster2pgsql

I'm new to postgis and raster file format. i currently working on netcdf files and i want to import it into postgis through curl command line tool but its failed for me.so i jump on to GDAL v1.9.2 ...