Questions tagged [inverse-distance-weighted]

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

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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: ...
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0answers
59 views

Cross-validation error threshold in ArcGIS

I'm learning the Geostatistical Wizard toolset in ArcMap 10.4.1 and I am performing the cross-validation step in an IDW interpolation. I have done some research regarding the process of cross-...
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1answer
54 views

point count from in Inverse Distance weighting procedure - QGIS

I have conducted an interpolation using IDW procedure. I have vectorized the interpolation in order to be able to specify a 3 class clasification. I have additional point dataset indicating the ...
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1answer
252 views

IDW Interpolation in QGIS gives weird values

I'm trying to do an IDW interpolation with QGIS tool. But i'm really surprised by results. Interpolation values aren't similar as shape values. I used a power of 0.2 to get a smooth raster. Somebody ...
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0answers
52 views

Constraining an IDW interpolation [closed]

I am running an IDW on a data set that represents point values of water current speed. I would like to run the IDW only within the water area of another shapefile that shows the shape of the water ...
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1answer
1k views

Creating a python script to import an excel spreadsheet, create shapefile and do some analysis [closed]

I am trying to write a script that does the following. Imports an xls file containing x, y, and other columns with data. I want to make this into a point shape file. I want to take that point ...
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2answers
303 views

Extrapolating surface in ArcGIS Desktop?

I'm trying to calculate the volume of a landform under water in ArcGIS and here's what I decided to do: Convert the raster of the bathymetry that I had to a gridded point dataset using Raster to ...
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1answer
111 views

Interpolating points conditionally

I have two sets of data. One comprises all home sales in a given area, where each data 'point' is actually a polygon representing the lot that was sold. The other set comprises arrests made in the ...
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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 ...
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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 ...
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1answer
466 views

Interpolated raster not aligned with the vector data

I have loaded some tab delimited text data into QGis to interpolate the points. When I get to the interpolation (IDW) part everything breaks down. The output raster file does not align with the ...
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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'...
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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 ...
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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 ...
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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 ...
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1answer
686 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 ...
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1answer
632 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?
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0answers
79 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 ...
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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 ...
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1answer
729 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, ...
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1answer
241 views

Inverse distance weighting variable search radius based on third variable [closed]

I am trying to perform inverse distance weighting (and possibly kriging), but want to base the search radius on a third variable: high population density -> small search radius low population density ...
2
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1answer
602 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 ...
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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 ...
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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.
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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 ...
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1answer
557 views

Specifying the “idp” and the “nmax” in the krige.cv function

I'm performing IDW interpolation using the idw R function from the gstat package. For the purpose of determining what combination of "idp" and "nmax" produces the lowest RMSE in leave-one-out-cross ...
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1answer
619 views

Applying mask in ArcGIS Geostatistical IDW?

I'm finishing an analysis of approximately 850 archaeological assemblages in the Mediterranean, and I've successfully run IDW in Geostatistical toolbox (ArcGIS 10) to generate the results I like. I'm ...
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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 ...
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0answers
317 views

ArcGIS Interpolation IDW and Spline, extreme values [closed]

I am trying to interpolate air pollution data that is displayed in 1x1 Km points in ArcGIS. I am having two issues: When I try to interpolate using IDW, the software freezes at 94% "building search ...
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0answers
138 views

Understand ramp color interpolation using QGIS 2.12

I try to understand the color ramp in TIN and IDW interpolation. I work with height points layer. The low value in 8 and the highest value is 584. With the interpolation plugin i create TIN raster ...
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0answers
179 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 ...
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1answer
451 views

IDW with QGIS from a vector points file within a mask

Given two inputs: A shapefile: points A raster: mask I want to interpolate the points within the extent of the raster except the NoData pixels that i want to use as a mask. NoData pixels are the ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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0answers
316 views

How to create contours from an IDW raster

I'm new to QGIS and am trying to create vector contours from this IDW raster. I followed Ujaval Gandhi's "Interpolating Point Data" tutorial step by step but am not getting the same results for step ...
2
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1answer
687 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 ...
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1answer
247 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 ...
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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, ...
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0answers
172 views

Looking for a tool like (IDW) for raster

I am looking for a tool that gives the same outputs like the IDW, but for rasters instead of points. I have a Corine land cover raster layer in ArcMap 10.2 with different friction values, displaying ...
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1answer
433 views

Add Layers to Map Display from script with default symbology

I have a script that runs IDW iterations and I'd like for the files to be automatically added to the map display after they are produced and contain the default symbology that ArcMap generates when ...
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1answer
203 views

Parameters for optimizing interpolation in ArcGIS for Desktop?

Is there any criteria to know the most proper parameters for an interpolation method in ArcGIS (such as, for IDW: Neighbors (min and max), sector type, semiaxis length, angle, search neighborhood)? ...
2
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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 ...
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2answers
2k views

Cell Size parameter for IDW (Spatial Analyst) tool

I am attempting to use the IDW (Spatial Analyst) tool in a Python script however I am a bit confused on what to put for the "Cell Size" optional parameter. When using the tool within ArcMap it seems ...
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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 ...
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1answer
156 views

How to export a IDW raster while keeping the search radius data

I want to export my IDW rasters that I made in ArcGIS to QGIS, however when I export my raster, the values are there but are no longer displayed. They are stored within each cell and are not ...
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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 ...