17
votes
Accepted
R gstat krige() - Covariance matrix singular at location [5.88,47.4,0]: skipping
This error is commonly returned because you have duplicate locations. You can check this using the sp::zerodist function.
To remove duplicate locations you call sp::zerodist within a bracket index.
...
- 29.5k
16
votes
Plotting map resulted from kriging in R
In order to interpolate prices with kriging you first need to convert your geographic coordinates to projected coordinates. Assuming you have them, below there is a reproducible example, showing a way ...
- 9,901
10
votes
Accepted
Performing Kriging in QGIS
The great thing about QGIS is its modular design, based on which you can use the geoprocessing engines of various other systems directly as tools in QGIS (GRASS, SAGA, GDAL, OGR, ...). In order to do ...
- 13.8k
10
votes
Which interpolation technique is suitable for a bathymetry of a small lake?
One alternative is spline interpolation as suggested in the related post:
Interpolation of multibeam bathymetry.
From QGIS, use the GRASS tool v.surf.rst:
Performs surface interpolation from ...
- 9,901
9
votes
Accepted
Strange spatial interpolation results from ordinary kriging
In a nutshell, the problem lies in a mismatch between data behavior and some (strong) assumptions you are implicitly making.
Diagnosis
The strongest of these is that the data are one realization of a ...
- 67.7k
9
votes
Accepted
Improve performance of a PostGIS st_dwithin query
The explain doesn't show an index coming into play, which could be for two reasons:
You don't have one. So make one with CREATE INDEX tree_gix ON trees USING GIST (geom)
Your data is in geographic ...
- 19.4k
9
votes
Accepted
QGIS: what is the difference between heatmaps and interpolation plugins?
Heatmaps and interpolations are completely different things though they might look similar.
A heatmap visualizes "hotspots" in the distribution of features on the map i.e. dense areas will be ...
- 902
8
votes
Performing Spline interpolation on GPS Track
Try using v.generalize tool from the Processing Toolbox. There are a number of algorithms in there that can generalize a line nicely.
Another possible solution could be the "Generalizer" ...
- 1,536
8
votes
Downscaling raster images in Google Earth Engine?
You can control the pixel size of an image by setting the scale parameter of ee.Image.reproject():
// Reference a Landsat scene.
var image_30m = ee.Image('LANDSAT/LC08/C01/T1/LC08_044034_20170614');
...
- 4,841
8
votes
Accepted
How to use GDALGridInverseDistanceToAPower in a python script
Yes, you can call this from a Python script. But you don't directly call the low-level C API.
First, take a look at the GDAL Grid Tutorial for background info. From the Python library, the relevant ...
- 39.9k
8
votes
Accepted
Replica of point layer data from attribute value in QGIS
The following script does the job:
layer = QgsProject.instance().mapLayersByName('Layer_Name')[0]
name_field = 'Name' # not mandatory
count_field = 'Count' # numerical field, mandatory
# make new ...
- 55.8k
7
votes
Mapping Precipitation Data
What you need to do to create a continuous surface representing precipitation is a process called interpolation. ArcMap has a number of tools to do this, based on a variety of statistical and sampling ...
- 8,926
7
votes
Interpolate data from multiple gpx tracks
Yes, there are such algorithms (see for example here, there and here) but since you seem to have only one single road, would it not be easier to do it by hand? (!). Using for example QGIS, you could ...
- 9,947
7
votes
Extracting raster values with polylines in QGIS
This is a bit of a late answer, but I thought it was worth contributing.
As a polyline is just a series of points you should be able to obtain the Mean value you want by converting the Polyline nodes ...
- 81
7
votes
Repeating steps based on different field using ModelBuilder?
There is not an Iterate Fields tool in ModelBuilder.
I can think of two possible workarounds:
Modify the model to run as a Python script. Define a list of the fields you want to use, and define a ...
- 8,926
7
votes
Accepted
Interpolating degree data using QGIS?
Interpolate the sine and cosine of the angle, and then convert back to an angle with the atan function. These functions are available in QGIS' expression engine. There is an atan2(dy,dx) function like ...
- 52.1k
7
votes
Accepted
How to calculate kriging weights?
Is it true that we're just using a different set of weight values than the 1/distance in IDW?
Yes, both IDW interpolation and Ordinary Kriging (OK) will calculate weights based on distance, but with ...
- 9,901
7
votes
Interpolate smoothly nodata values in QGIS
I got curious and tried the different fill nodata functions. As you can see the regular SAGA Close Gaps produced the least anomalies. It also took the longest.
- 2,009
6
votes
Accepted
Spatial interpolation of 30 weather stations to other areas
You can likely get a reasonable interpolation using a linear regression (assuming your 30 weather stations are a representative sample) using elevation, latitude and distance from the coast as ...
- 52.8k
6
votes
Accepted
Raster interpolation with gdalwarp, and replicating with python API
You have now a better way to do.
Since RFC 59.1 : GDAL/OGR utilities as a library, you can use gdalwarp from Python directly without using any call to the command line utility but using really the ...
- 28.7k
6
votes
Weird output when projecting/interpolating points on lines
I think you have a problem with your points shapefile and/or the projections (lines and points).
These commands are those of Shapely used by GeoPandas
From Coordinate of the closest point on a line
...
- 51.2k
6
votes
TIN Interpolation plugin in QGIS 3.0
According to the changelog, the TIN interpolation plugin has been removed, as it is now part or QGIS core.
To find it in Qgis 3.0, open the processing toolbox and search for Interpolation -> TIN ...
- 1,831
6
votes
Accepted
Smoothing/interpolating across images in an ImageCollection to remove missing data
You can replace the values using where().
// Replace masked pixels by the mean of the previous and next months
// (otherwise, how to deal with the first images??)
var replacedVals = composites.map(...
- 9,298
6
votes
PostGIS: Interpolate/Cluster geographic points to average points
A solution using PostGIS alone.
The Steps are as follows:
Generate clusters from the points
Get the centre of each point cluster
Generate a line that connects each cluster centre point (will also ...
- 1,738
5
votes
Accepted
"Topo to Raster" tool for QGIS?
No there isn't a QGIS analogue to TopoToRaster (actually ANUDEM)*. There isn't an analogue anywhere else that I'm aware of either for that matter.** (If you know of others please chime in.)
In brief ...
- 27.6k
5
votes
What resampling technique should be used when projecting aerial photos?
I know that this question is rather old, but I wanted to add my 2 cents, in case others come across this thread trying to answer the same question...
The previous answers are correct when you truly ...
- 67
5
votes
Accepted
Spatio-temporal block kriging with R package gstat?
In sp, SpatialPoints*, SpatialPixels* and SpatialGrid* (with * omitted or replaced by DataFrame) do support more than 2 spatial dimensions, as OP has done, but SpatialPolygons* and SpatialLines* do ...
- 1,914
5
votes
Accepted
Cross-validation of TPS and kriging outputs from the fields package in R
If you are just after a metric of performance, this is a fairly straight forward type of analysis to specify. 1) specify a model, 2) predict the model(s) at the data, 3) apply an accuracy/performance ...
- 29.5k
5
votes
Accepted
How to interpolate population data?
The short answer is: no, but it might be the best you can do without additional layers. The problem is that humans do not settle evenly. If all you have is populations of cities then IDW might be your ...
- 982
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