[GIS] Error in raster Analysis in QGIS

memoryqgisraster-calculatorsaga

I'm trying to conduct raster analysis in QGIS on a digital elevation model with a grid resolution of 5 cm. The disk size for the data set is 151 MB. When using default GDAL raster calculator it throws an error " Raster Calculator: Insufficient memory available for operation."

Can anyone suggest alternatives to QGIS raster calculator?

PS- I have tried using SAGA Grid calculator but on the import of the same dataset in SAGA, the software crashes.

The following are the hardware specifications of my desktop:

AMD FX6300 six core 3.5GHz

Installed RAM 4.0 GB (3.5 GB usable)

64-bit operating system

Raster info:

Driver
GDAL provider
GTiff
GeoTIFF
Dataset Description
E:\QGIS\practice_content\terrain_analysis_mining\new_files\DSM.tif
AREA_OR_POINT=Area
TIFFTAG_SOFTWARE=pix4dmapper
Band 1
STATISTICS_MAXIMUM=79.582763671875
STATISTICS_MEAN=52.49497241844
STATISTICS_MINIMUM=34.057125091553
STATISTICS_STDDEV=10.220585082683
Dimensions
X: 14249 Y: 26318 Bands: 1
Origin
408714,1.6928e+06
Pixel Size
0.05142,-0.05142
No Data Value
-10000
Data Type
Float32 – Thirty two bit floating point
Pyramid overviews
Layer Spatial Reference System
+proj=utm +zone=43 +datum=WGS84 +units=m +no_defs
Layer Extent (layer original source projection)
408713.6688200000207871,1691448.5592900000046939 : 409446.3524000000325032,1692801.8308500000275671
Band
Band 1
Band No
1
No Stats
No stats collected yet

Best Answer

Try to divide raster into parts and then use raster calculator - your DEM is very high detailed and huge, I mean

Related Solutions

[GIS] Cutting out depth information in raster. Calculating volume in Qgis

I believe you can use some map algebra (raster > raster calculator) before you can preform your volume measurements in grass.

Assuming that your bathymetric data use positive values to represent the sea depth, and using your example for the range as 50 the min_depth and 200 the max_depth. For each of the raster cells you need to "remove" anything below the 200 and above the 50. You have 3 possible situations:

your cell depth is higher than the max_depth

(@bathymetry > 200)
your cell depth in the min_depth - max_depth range

(@bathymetry <= 200) * (@bathymetry >= 50)
your cell depth is lower that your min_depth

(@bathymetry < 50)

In case 1 the size of the water column will be the entire size of our range:

(@bathymetry > 200.0) * (200.0 - 50.0)

In case 2 the "water column" is from your bathimetry depth until the minimum value of the range:

(@bathymetry <= 200.0) * (@bathymetry > 50.0)*(@bathymetry - 50.0)

In case 3 there is no useful "water column" for your specie therefore it would be:

(@bathymetry <= 50)*0.0

Since the 3 cases never occurs at the same time, all we need is to sum the expressions:

(@bathymetry > 200.0) * (200.0 - 50.0) + (@bathymetry <= 200.0) * (@bathymetry > 50.0)*(@bathymetry - 50.0) + (@bathymetry <= 50)*0.0

Since the last expression is always zero, the is no point in including it:

(@bathymetry > 200.0) * (200.0 - 50.0) + (@bathymetry <= 200.0) * (@bathymetry > 50.0)*(@bathymetry - 50.0)

And the generic version of the expression would be:

(@bathymetry > max_depth) * (max_depth - min_depth) + (@bathymetry <= max_depth) * (@bathymetry > min_depth)*(@bathymetry - min_depth)

After this, you can use the output raster in r.volume to sum all "water columns" values

[GIS] Clipping raster takes forever in QGIS

I may be misreading something here, but I see the image as a 1 degree by 1.5 degree area and the pixel size is 0.00027777 degrees. Just off the top of my head, if the value is decimal degrees, I think that would make the pixel size approximately thirty meters.

In looking at the screen shot, I am seeing an EPSG Zone of what I believe is 32622 (which is in the Northern Hemisphere UTM 22 N) and OTF is turned on.

I do not believe you want a negative value as large as is being displayed for the "Y" coordinate.

This is approximately where the coordinates plot out if using the that zone.

The Red rectangle depicts the boundary of that zone.

So here are a couple of options.

Option 1. Import the image into a project with OTF turned off and use EPSG Zone 31983 UTM 23 S

Here is a picture of that zone

This should match the metadata of the image, but I do not know if it will solve the clipping and export issue.

Option 2.

This is the one I would try first. Import the image using EPSG 4326, clip, and export it, then you could reproject it as necessary.

I agree with @user30184 that it appears to be EPSG 4326 after further investigation of the metadata. The pixel size of 0.0002777777 degrees would make sense if the image was Geographic, rather than projected.

Best Answer

Related Solutions

[GIS] Cutting out depth information in raster. Calculating volume in Qgis

[GIS] Clipping raster takes forever in QGIS

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