Questions tagged [inverse-distance-weighted]

Inverse Distance Weighting (IDW) is a method of interpolation.

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23
votes
1answer
28k views

Choosing IDW vs Kriging Interpolation for DEM creation?

I'm trying to create a DEM using point data spaced very regularly about 10m apart. The area I am interpolating is an educational facility with many flat parking lots and football fields but still has ...
10
votes
1answer
728 views

SAGA Inverse Distance Weighting in QGIS - How to Set Minimum Number of Points?

I am analyzing a postGIS point dataset in QGIS version 2.8.2, about 200k features total. To calculate weighted average values I am using the Inverse Distance Weighted interpolation technique. However, ...
6
votes
2answers
6k views

Picking coefficient in Inverse Distance Weighted method of QGIS?

I'm using QGIS 1.8.0 to interpolate weather data. This is, I have a weather station located in say, A and C. With the Inverted Distance Weighting or Triangular Interpolation methods, I can know/...
6
votes
2answers
184 views

Why do I get a shattered-glass effect when I turn on hillshade for my IDW surface?

I made an interpolated IDW surface with a cell size of 500. In the symbology tab of ArcGIS, there is the "Use hillshade effect" checkbox underneath the classification area. When unchecked, my surface ...
5
votes
2answers
178 views

Understanding Inverse Distance Weighting Bulls Eye Effect?

Is the Bulls Eye Effect generally caused by a sample point with a high value being too far from other sample points? Or rather a sample point with a higher value than others close to it? What ...
5
votes
2answers
466 views

How to calculate kriging weights?

In Esri's documentation on how to make a prediction in Kriging, I couldn't figure out the linkage between the semivariograms and the prediction process from reading the description therein: After ...
4
votes
2answers
402 views

Defining number of cells in sample grid for IDW?

I'm trying to make IDW in R. In my tutorial, I found this approach which is easily understandable, expect of one point - why they used n = 6000 ? How did they established the value to create a grid ...
4
votes
1answer
521 views

Does IDW interpolation in ArcGIS Geostatistical analyst work as exact interpolation method?

As we know, Inverse distance weighted (IDW) is an exact interpolation method, which means the interpolated values of the known samples should be the same with its original observed values. But when I ...
4
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0answers
178 views

Interpolating species data from sample points in a small area [closed]

I have sample data from a small site (10 acres) which shows the number of occurrences of a particular species of snail over two sampling periods (fall and spring sampling). I want to try and ...
3
votes
2answers
4k views

What's wrong with my IDW interpolation function (Python)?

Original Question Can anyone see what's wrong with my custom IDW interpolation below? I know there are existing libraries that can do this for me, but for various reasons including educational and ...
3
votes
1answer
616 views

SAGA IDW interpolation algorithm has been changed?

Yesterday, I try after a long time to make an IDW interpolation on a point layer in Qgis 2.18 with SAGA tools. I use same parameters as before on Qgis 2.14, but the result is quite different. Raster ...
3
votes
2answers
174 views

How to use GDALGridInverseDistanceToAPower in a python script

I'm trying to use GDAL in a python script to do an inverse distance interpolation. Within the C documentation API I found GDALGridInverseDistanceToAPower function but I don't know how/if I can call ...
3
votes
1answer
144 views

How do Natural Neighbor and IDW assign values to pixels?

According to ESRI's help files, NN interpolation calculates a value for a "query point", yet the output is ofcourse a raster. I understand how the value of this query point is calculated based on ...
3
votes
1answer
95 views

Interpolation of data points

I have a layer of points that represent bus stops. Each point has a value (quality of service, between 0 and 100). I need to create a grid (resolution 25m) by interpolating the points values. For ...
2
votes
2answers
267 views

Getting similar IDW results using Spatial and Geostatistical Analysts for spatial interpolation of data with many zeros?

My data are plant biomass data from hundreds of sites. Most sites have zero biomass; these zeros are real. Thus, my data violate most assumptions of geostatistical interpolation methods (confirmed ...
2
votes
2answers
2k views

How to interpolate population data?

I have population data (inhabitants per city and year) of 31 cities of the DR Congo for the years 1960, 1970, 1980 and 1990. I want to interpolate the population of all cities for the year 1990, to ...
2
votes
2answers
327 views

Making data table using linear kriging interpolation with variogram in R

I have a table of data with such structure: longitude_for_data = c(32,68,89,145,176, -14, -42) latitude_for_data = c(22,98,21,13 , 16,-134,-102) Z_for_data = c(30,40,60,70 , 20, 40, 100)...
2
votes
1answer
246 views

Why does the use of barrier lines significantly increase idw processing time?

The IDW tool's documentation states that using barrier lines will significantly extend the processing time. It does not explain why this happen. Is anyone able to provide an insight into the inner ...
2
votes
2answers
330 views

Using buffer from IDW in ArcGIS 3D Analyst for flood spread?

I have a line in the centre of a road, with the roads elevation attached to its properties. By using Generate Point along lines --> Add Surface Information --> Adding 10 cm to that, and then IDW 3d ...
2
votes
1answer
831 views

Inverse Distance Weighted (IDW) Interpolation with Radial Basis Function (RBF) in R

I want to perform an IDW interpolation with R. I am aware that I can do that with gstat::idw. But I want to change the parameter 'idp' with a radial basis function (RBF): where is the ...
2
votes
2answers
2k views

Interpolating data using QGIS? [closed]

I am trying to interpolate distribution value of rain using IDW (inverse distance weighting) method using quantum gis. What steps do I need to undertake? The input layer data which I used there are 2 ...
2
votes
1answer
30 views

Including buffer to IDW in ModelBuilder

I have created a model with ModelBuilder to interpolate values with the IDW tool, iterating through rows. How can I restrict interpolated values to regions within a 20km buffer? I tried setting the ...
2
votes
1answer
116 views

Cannot add ArcGIS ModelBuilder output to table of contents

I've made a model that creates some points with Z value and a buffer, which I then do a 3D analyst IDW on, and a Cut Fill analysis. The model input is a line along with af DEM/Raster, and some names ...
2
votes
1answer
685 views

choice of number of neighbors in IDW

I am not so familiar with 'interpolation' math, albeit I grasp the underlying logic. I was wondering if there is a rule of thumb in the choice of the number of neighbor points to use in IDW ...
2
votes
1answer
21 views

Running IDW, but values are '<1' not 0.934 so they are Strings not Doubles

I am trying to use some interpolation tools for analytical data of concentrations of Benzene for monitoring wells. A decent amount of our values for Benzene are '<1' (not 0.943 or 0.345) because of ...
2
votes
1answer
683 views

IDW interpolation of values from raster in ArcGIS

I've been tasked with obtaining z-values for a large point set from a 2 m raster, but rather than extracting values directly from the raster, or with bilinear interpolation, I've been asked to use ...
2
votes
2answers
210 views

What does 'Weight Field' in IDW interpolation mean?

I am trying to figure out how the Weight Field option of Geostatistical Analyst IDW in ArcMap 10.3 works. On IDW - ArcGIS Desktop Help I can find just this simple explanation: Used to emphasize ...
2
votes
1answer
601 views

How to compare a TIN and IDW-derived raster DEM quantitatively?

I'm a student and got the assignment to compare a TIN with a height raster 'quantitatively' and I'm not quite sure how to proceed. I tried subtracting the one from the other but it doesn't seem to be ...
2
votes
1answer
631 views

How to automate the QGIS Raster Interpolation Plugin using python console?

I have a rainfall data from 1961 to 2015 for each day of this years. I need to create a raster for each day with this configuration. Do you know how to automate this using this plugin and python?
2
votes
1answer
235 views

give importance weighting to sample points in an IDW-interpolation

I am trying to make an IDW-interpolation in arcgis 10.1. In my sample file i have points with the same x,y and z values. According the arcgis-resource-site, the points are considered duplicates and ...
2
votes
1answer
624 views

How to make polygons from interpolated points?

My goal is to make a shapefile with polygons for variable rate fertilizer application within a farm field. I have a point shapefile with soil sample values (pH, P, K and so on) and a line/polygon ...
2
votes
1answer
470 views

Cross-validation and optimal p power in IDW

I use the "Geostatistical Wizard" in ArcMap 10 to do my interpolations. For example, when I do IDW and I want to decide for the optimal p power or the optimal number of neighbors that will contribute ...
2
votes
1answer
38 views

Interpolate Line Tool giving different results?

I have been using 'Interpolate Line' Tool in the 3D Analyst tool pack to create a profile graph so I can analyze interpolated results gathered from an IDW created surface. However, when I use the tool ...
2
votes
1answer
146 views

Expanding IDW interpolation to borders of country in ArcGIS Pro? [duplicate]

I am new to ArcGIS. I have a data set with air pollution concentrations for 20 locations in the Netherlands. I would like to interpolate this data with IDW, so that I can estimate the approximate ...
2
votes
0answers
78 views

WEKA for IDW evaluation IN QGIS

intento evaluar una interpolación IDW realizada en QGIS y desconozco la manera de validar o evaluar su ajuste (y con cuales herramientas). Pero he descubierto WEKA como una alternativa para la ...
2
votes
1answer
65 views

Elevation profile and chemical concentrations

I have a IDW layer showing the pattern of a chemical concentration. I have also created an elevation profile across the same area. Is there any way to include the IDW measurements with my elevation ...
2
votes
0answers
39 views

Determining search variable when using Inverse Distance Weighted Interpolation? [closed]

When using IDW interpolation in ArcGIS, how should I determine the number of nearest input sample points to be used to perform interpolation? The default number is 12, but it may be incorrect.
1
vote
3answers
2k views

Which interpolation method for noise mapping?

I want to create a noise map with measured point data. But I want to have a planar representation, so I need an interpolation method. Which one is the 'best' for measured noise data? I prefer 'IDW'...
1
vote
2answers
585 views

Iterating through z-values in ModelBuilder

I have a series of fields that I am trying to run the IDW tool against. I'm looking for a way iterate through the feature class, using a different field as the z value each time. This is my data: ...
1
vote
2answers
735 views

Using ArcGIS API interpolation functions (idw, kriging, splines) in my own dataset?

Does ArcGIS API provide interpolation functions, like if I want to interpolate from my own set of values? I know that ArcGIS provides functions for interpolation like IDW, Spline and Kriging etc, ...
1
vote
1answer
188 views

Checking accuracy of IDW using ArcGIS Desktop?

I performed IDW using ArcGIS on 121 evenly distributed samples and generated a surface. How do I check the accuracy of the method?
1
vote
1answer
2k views

Creating Digital Elevation Model from Contour Data using QGIS? [duplicate]

In ArcGIS I used to create DEMs from contours with ease. However, we recently opted to stop using ArcGIS (for various reasons), and switching to QGIS. The reason I use contour data is it is all ...
1
vote
1answer
1k views

What is the unit of “output cell size” in IDW in ArcGIS?

I have a wind speed point data which I interpolated using IDW. While interpolating, it asks for output cell size. I am confused as in it is in which unit? My data is in UTM projection and WGS 84 ...
1
vote
1answer
113 views

How can I get the value of a point that falls between 2 points of another layer?

How can I get the value of a point that falls between 2 points of another layer? I have a Shapefile of points with values representing the distance from an origin (blue in the example bellow) at ...
1
vote
2answers
274 views

Performing IDW interpolation and mean estimation on county level using ArcGIS Desktop?

I am absolutely new to GIS. I have imported a map with information in the counties of Germany. Additionally I have added a layer with information on SO2 concentration at various measuring stations in ...
1
vote
1answer
168 views

IDW with buffer in QGIS

I'm very new to QGIS and am having some issues using the SAGA IDW tool. I'm attempting to perform an interpolation using the 10 closest sample points and an inverse distance power of 2. I would like ...
1
vote
1answer
495 views

Is there a minimum number of required samples/ data points for IDW Interpolation in ArcGIS for Desktop?

I am interpolating air pollution values from 6 data locations using IDW in ArcGIS. I know that more the number of points, more reliable the results are. But, I am not sure if a minimal number of data ...
1
vote
1answer
37 views

Finding creator of Inverse Distance Weighted method?

I am interested in the very first person who invented the Inverse Distance Weighted method or the very first reference that this method was mentioned. I tried to search on Google but could not get ...
1
vote
1answer
65 views

Using Row Iterator and IDW in ModelBuilder?

I am using ModelBuilder to perform inverse distance weighting. I would like to interpolate values using a point file with values for several unique dates - resulting in a raster dataset for each ...
1
vote
1answer
187 views

IDW Interpolation pyqgis QGIS3

I try to create a interpolation with the follow script, the problem is that when the program tries to write QgsGridFileWriter, qgis crashes. The problem is that the different examples are to lower ...