Questions tagged [smoothing]

smoothing is a generalization process that can remove any extreme values in a linestring or surface or just smoothens a linestring or polygon boundary by adjusting their vertex positions

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Bringing river bed to the same height as surrounding ground in QGIS

I have a DEM containing the current flow networks in an area. I also have a shapefile showing the same flow network. I would like to derive a new river network to see how water would flow if the ...
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5 votes
4 answers
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Smoothing out lines created by raster layers

I have a line layer that has been formed from a raster layer (It was a skeletonised raster layer). It now has a lot of unwanted vertices and needs smoothing out before further analysis. I have tried ...
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1 vote
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Smoothing/interpolating NDVI to remove missing data and outliers

I want to get the smooth NDVI data and want to remove the outliers, I want to know how can I achieve it. I attach my code, I tried to smooth it with 16 days window, but it still seems to have a sudden ...
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Contour Polygon Alternatives on QGIS

I am trying various ways to make polygons from raster data using 1 m DEMs. I am using QGIS 3.16 Hannover I have tried vectorizing my data, which does work OK, but I would like smoother boundary lines ...
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No difference between Savitzky-Golay 2nd order and 3rd order polynomial curve

I don't understand why there is no difference between Savitzky-Golay 2nd order and 3rd order polynomial curve? Perhaps the 3rd order polynomial curve is overfitted, not sure but the concern is yet not ...
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2 votes
1 answer
94 views

Removing sharp curves using ArcPy

I have been trying for some time to find a way to eliminate the exaggerated curves in a contour curve that I usually obtain from line 0. The idea is to obtain a polyline that is more or less faithful ...
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1 vote
0 answers
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How to use a temperature raster (e.g., PRISM) to constrain temperature values in a thin plate spline regression and interpolation

I have point data with temperature, latitude, longitude, and elevation. I am interpolating across space to the extent of those points, and have been using elevation as a covariate in the fields::Tps. ...
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What is the difference between using interpolate() and predictSurface() on a thin plate spline regression?

I have a set of points (not evenly distributed across space), which have location (lat and long), temperature, and elevation. I want to interpolate/create a raster from those points that have ...
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1 vote
1 answer
272 views

How to smooth the DTM?

I had a point file of an area around 70 km^2 collected through field survey using Auto Level. The survey was carried out in the lines 25 m apart. I converted the readings from auto level into point ...
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1 vote
1 answer
28 views

Orfeo Toolbox output rasters are 300x larger than inputs of the same size

I am trying to use Orfeo Toolbox CLI to do some processing, e.g. Smoothing: otbcli_Smoothing -in path/to/mosaic.tif -out output/smoothing.tif uint8 -type mean For now, the input, mosaic.tif, is just ...
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1 vote
2 answers
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Interpolate a new 3D surface between two other 3D surfaces

I have two 3D Raster surfaces which are flood height surfaces for two different flood heights. They each have XYZ coordinates. I now wish to generate a third surface BETWEEN these two surfaces at ...
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1 vote
1 answer
105 views

Resolving trade off between smoothing via polynomial fitting and simplify-like algorithms (do not eliminate vertices)

I am struggling for a few weeks to use Python to smooth various linestrings and bumped into a conundrum. There seems to be a trade-off between using techniques that apply parametric curve fitting and ...
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2 votes
1 answer
92 views

Editing existing polygon vertices to create smooth curves using ArcMap

I'm editing a really detailed polygon in ArcMap. The vertexes of the polygon are connected with an straight line. I want to convert them in a smooth curve. While creating the polygon I use the "...
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2 votes
1 answer
128 views

Smoothing all the intersection for GPX track points?

I have a.GPX Track file that has too many intersections. I want to smooth out due to all the intersection Currently, I'm trying to figure out a way to smooth out this track file. The intersections are ...
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3 votes
1 answer
318 views

Creating a heatmap from TIFF file in QGIS

The task which I am currently working on, has us to create a kind of a 'heatmap' with KDE (or similar). As a first step I vectorized the TIFF File and now it looks like this: The end product should ...
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3 votes
1 answer
129 views

How to get a smooth transition between startpoint and endpoint of a line in QGIS?

I have a layer with a few lines. They look very smooth in general, but there is a sharp edge at the start/endpoint of the line. Hot to eliminate that and get the blue dotted result line there?
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1 answer
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Smoothing spline/raster in ArcGIS

I have a spline, but it turned out to be angular at the ends, is there a tool or how can I smooth the raster in ArcGIS?
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0 answers
29 views

How to smooth interior polygons of one shapefile

I have a shapefile that includes the boundary of a field plus many interior polygons that represent levels of NDVI - we'll say High, Medium, and Low. The larger areas have jagged, irregular edges. ...
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1 vote
0 answers
125 views

How to smooth discrete raster data with GDAL in C++?

I am using GDAL in C++ for upsampling land-cover raster data. When upsampling, I would like to smooth out the edges, so that I do not get aliased stairs but nice diagonal lines. Essentially, the "...
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3 votes
0 answers
39 views

Turn disjoint polygons into tessellation

I have a set of points that have labels. These labels represent geographies; however, some of the labels are wrong. Like in the picture below So after running some analysis, I end up with a set of ...
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2 votes
0 answers
304 views

Smooth contour lines/correctly extract contour lines from a DEM in QGIS

I have a DEM obtained as a result of the interpolation of elevation points TIN Interpolatin: I extracted the contour lines in QGIS and the result is this: After I tried to apply the Line Smoothing ...
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3 votes
1 answer
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A simple way to merge lines separated by a space in QGIS

In QGIS after creating contour lines by extracting them from a DEM (Extraction > Contour) and smoothing them (Line Smoothing) I noticed this situation: In order to smooth out the corners ...
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1 vote
0 answers
157 views

Which resolution is appropriate for resampling a raster in a specific CRS in QGIS 3.6? [closed]

I'm trying to resample a raster file to obtain smooth interpolated levels in EPSG:3120 - Pulkovo 1942(58) / Poland zone I projection. (following the steps in this answer) 1. Using the raster ...
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6 votes
2 answers
2k views

Making elevation contours of raster smoother using QGIS

I am using QGIS 3.6. I have raster of Europe map which I want to make a colored relief model. After duplicating the layer, used hillshade on backward layer and colored the upper layer interpolation >...
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  • 119
1 vote
1 answer
51 views

Seeking algorithm that can re-locate vertices on linestring so that line does not intersect land polygons

I'm currently working with GPS data gathered from boats. The data has low temporal resolution (every 5 minutes) which causes the linestrings that display the boat's trajectory to be jagged. An example ...
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1 vote
1 answer
123 views

Setting correct start and end time series for Savitzky-Golay in R

I am trying to smoothen my raster stack using Savitzky-Golay method. I am following the workaround from HERE but my problem is setting start and end of my time-series raster. My series of images were ...
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  • 161
0 votes
1 answer
158 views

Raster smoothing - assigning each raster the average value of its neighbors

I have a raster world map of population densities at a resolution of 30 arc seconds. For each raster, I want to find out the average density of neighbors within a certain distance (e.g. 0.1 degrees). ...
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2 votes
1 answer
316 views

How can I smooth LineString coordinates with 1D Gaussian Filter?

I'm trying to smooth a LineString through 1D Gaussian Smoothing and I'm having a doubt on the steps required to implement it, regardless of programming language. I couldn't find by myself anything ...
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2 votes
1 answer
2k views

Smoothing polygons in QGIS? [duplicate]

I vectorised an image and all my polygons have extremely jagged edges. What is the best way to smooth these polygons?
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2 votes
0 answers
129 views

Smoothing MODIS LAI? [closed]

I am trying to smooth 8 days LAI data from MODIS and managed to work around it with several algorithms such as loess, Savitzky–Golay, smooth.spline etc. This is pretty much going well if the level of ...
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3 votes
1 answer
70 views

Exporting render of polygon after applying smooth geometry command using QGIS?

I have recently discovered the smooth($geometry,x) command in QGIS which is very convenient for me. However, when exporting polygons, the "smoothness" obviously goes away as the vertices are untouched ...
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2 votes
1 answer
404 views

Blurring raster data across tile boundaries?

I have a raster dataset that is made up of 280 tiles, 51Gb total. I need to smooth/blur the data, retaining the same resolution. I would like to blur across tile boundaries, where possible, so that ...
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2 votes
1 answer
3k views

GEE - Using Savitzky-Golay filter over an Image Collection [closed]

I'm trying to generate a smoothed MODIS(MOD11A2) time series by using the Savitzky-Golay filter. There is this github repo https://github.com/Fernerkundung/EarthEngine_scripts/blob/master/...
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1 vote
1 answer
41 views

How to apply smoothing filter only to way bigger than specified number of nodes, length, area?

I am try to smooth data obtained by vectorization of a raster image by applying a series of filters in GRASS GIS. Once of steps involves using the Douglas-Peucker filter. However, I need to apply it ...
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9 votes
1 answer
7k views

Smoothen Line vector QGIS

I am working on a publication and would like to make my schematic visually pleasing. The amount of detail is too high and the image would be better If I could simplify and smooth my line and polygon ...
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6 votes
1 answer
2k views

Data smoothing of Sentinel-2 NDVI time series chart in Google Earth Engine?

I am exploring Sentinel-2 time-series NDVI with Google Earth Engine. In another post I learned how to plot a NDVI time series chart. I know that there are many smoothing methods for reducing NDVI ...
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5 votes
3 answers
1k views

Smoothing raster with binary cell values

Main question towards the end. Details follow now: I have a slope raster Region: Bern, Switzerland CRS: EPSG:2056 - CH1903+ / LV95 - Projected Extent: 2587757,...
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1 vote
1 answer
52 views

Mapnik upsampled raster isn't smooth

I'm using Mapnik to show a map with hillshading. It works well when displaying it up to my tiff's native resolution and a little bit above, for instance at zoom 13 (dataset is SRTM30): But then if I ...
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2 votes
0 answers
68 views

World DEM speckled outcome solution

I have a world digital elevation model which has been classified into 5 showing the different heights. My issue is that viewing and printing this image as it is results in a speckled look due to the ...
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1 vote
1 answer
165 views

Generalizing slope raster in Mapinfo?

I am working on calculating a slope raster in Mapinfo using a 15cm DEM derived from a LiDAR point cloud and the output data will have 3 predefined breaks displayed so I need to blur those relatively ...
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2 votes
0 answers
110 views

Importing .geotiffs and wavelet denoise plug-in - GIMP

I am trying to run the wavelet denoise plug-in tool on GIMP to smooth a .geotiff. Unfortunately when I import the .tiff, the spatial refernece is lost and the image appears black. My goal was to ...
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2 votes
0 answers
57 views

Obtaining a smoothed DTM?

I am use AcGIS 10.1 and have a DTM with an 8 m grid resolution. Which tool could I apply to smooth the surface?
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2 votes
0 answers
35 views

Smooth Data Values Across Geographies with Zero Population

Looking to fill in gaps through generalizing a population count across U.S. counties. I.e., if a county has 0 population, but is surrounded by 5 non-zero counties, then change the 0-population county ...
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  • 533
1 vote
1 answer
75 views

Remove small interstices on the edges of a polygone

How can I remove the white interstices on the edges (and interior) of a polygone or polyline, as represented in the first figure below? I want to get smooth and continuous edges, capturing the global ...
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2 votes
0 answers
405 views

Optimized smoothing of stream lines generated from Arc Hydro? [closed]

Has anyone found an effective ArcGIS 10.3.1 workflow for smoothing streamlines generated from ArcHydro...or hydrology in general? (Fill -> Flow Dir. -> Flow Acc. -> Stream Def. -> Stream Seg.-> ...
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2 votes
0 answers
227 views

Smoothing borders of polygons taking a layer of points into account

I'm trying to smooth borders that separate clusters of points. GRASS instrument v.generalize.smooth works pretty well, except that in some cases the points end up on the wrong side of the smoothed ...
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1 vote
0 answers
92 views

Avoiding tiling/mosaicing in resulting image when Pan-sharpening Gram-Schmidt?

I mastered to georeference some declassified Hexagon satellite imagery from the 60s and would like to use it to pan sharpen a current Sentinel satellite image (already done as RGB). It is very ...
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3 votes
0 answers
165 views

Why do I get invalid elements (polygons), when smoothing a vector layer (smooth geometry)?

The problem occurs, when using the commands "Smooth geometry" or "v.generalize.smooth" in QGIS. The shapefile, which I want to smooth, shows a flood water level and looks like this: The water level ...
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9 votes
1 answer
13k views

QGIS Raster map, smoothing pixels

I am trying to generate a map in Qgis which makes it possible to see the temperature of a region during a heatwave. This was a great succes. However, I want to add shades as well, since shades lower ...
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  • 285
1 vote
0 answers
311 views

GRASS r.denoise error

I have installed r.denoise, put mdenoise into QGIS2.18/bin and installed "pip install pyproj". However when I try to run r.denoise on STRM DEM, a get this error: ERROR: Unable to open file <...
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