Raster from XYZ csv format

Question

I have a large csv file of 3 columns of x y and z values. I want to do the following: 1. How to convert that csv into vector shape file (points). 2. How to convert the obtained points in step 2 into geo raster. 3. Lets say a set of separate point file in "shp" format how to extract the values from the raster obtained in step 2 into new the csv file so I can perform so statistics on it.

The issue is that I'm new to geo-processing using python, for example for step 2 I used to do that easily in R using "raster" package and for step 3 also using "extract" function in "raster" package. However, in python I can do step 2 in geopandas but step 2 and 3 no simple answer is available.

The normal procedure is converting directly XYZ to Raster. With GDAL tha's trivial. — LuisTavares
– LuisTavares, Commented Jun 16, 2019 at 10:21

alphabetasoup · Accepted Answer · 2019-06-18 21:07:45Z

1

This exact case exists in the GDAL documentation.

Assuming your data, dem.csv, is like:

Easting,Northing,Elevation
86943.4,891957,139.13
87124.3,892075,135.01
86962.4,892321,182.04
87077.6,891995,135.01
...

You create a VRT to describe it:

<OGRVRTDataSource>
    <OGRVRTLayer name="dem">
        <SrcDataSource>dem.csv</SrcDataSource>
        <GeometryType>wkbPoint</GeometryType>
        <GeometryField encoding="PointFromColumns" x="Easting" y="Northing" z="Elevation"/>
    </OGRVRTLayer>
</OGRVRTDataSource>

Or, if the CSV lacks columns, you can specify your GeometryField like this:

<GeometryField encoding="PointFromColumns" x="field_1" y="field_2" z="field_3"/>

Save that as something likedem.vrt for use in later commands.

Then to interpolate with gdal_grid and produce a GeoTIFF output:

gdal_grid -a invdist:power=2.0:smoothing=1.0 -txe 85000 89000 -tye 894000 890000 -outsize 400 400 -of GTiff -ot Float64 -l dem dem.vrt dem.tiff

answered Jun 18, 2019 at 21:07

alphabetasoup

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8 Comments

aminevsaziz Over a year ago

The issue here is 1. the output is somehow vertically flipped ...2. using python API it produce 512kb Tiff and 3. How to modify the coordinates system for the faster and 4. How to speed the python gdal API because it's extremely slow compared to R

alphabetasoup Over a year ago

I'm not recommending the use of Python.

aminevsaziz Over a year ago

Then what language we use ?

alphabetasoup Over a year ago

It's possible to use the GDAL Python bindings as you have been; I just don't like them. The last block of code is simply the command line; the others are snippets of text files.

aminevsaziz Over a year ago

How about GMT how to use it to grid the csv file

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