3D Analyst Tools ArcToolbox

IDW and Kriging Tools

IDW

How to use IDW Tool in ArcToolbox ArcMap ArcGIS ??

IDW Tool

IDW Tool, Raster Interpolation Toolset, 3D Analyst Toolbox

IDW

Interpolates a raster surface from points using an inverse distance weighted (IDW) technique.

1. Input point features

The input point features containing the z-values to be interpolated into a surface raster.

2. Z value field

The field that holds a height or magnitude value for each point.

This can be a numeric field or the Shape field if the input point features contain z-values.

3. Output raster

The output interpolated surface raster.

It is always a floating-point raster.

4. Output cell size (optional)

The cell size of the output raster that will be created.

This parameter can be defined by a numeric value or obtained from an existing raster dataset. If the cell size hasn't been explicitly specified as the parameter value, the environment cell size value will be used if specified; otherwise, additional rules will be used to calculate it from the other inputs. See the usage for more detail.

5. Power (optional)

The exponent of distance.

Controls the significance of surrounding points on the interpolated value. A higher power results in less influence from distant points. It can be any real number greater than 0, but the most reasonable results will be obtained using values from 0.5 to 3. The default is 2.

6. Search radius (optional)

Defines which of the input points will be used to interpolate the value for each cell in the output raster.

There are two options: Variable and Fixed. Variable is the default.

· Variable

Uses a variable search radius in order to find a specified number of input sample points for the interpolation.

oNumber of points—An integer value specifying the number of nearest input sample points to be used to perform interpolation. The default is 12 points.

oMaximum distance—Specifies the distance, in map units, by which to limit the search for the nearest input sample points. The default value is the length of the extent's diagonal.

· Fixed

Uses a specified fixed distance within which all input points will be used for the interpolation.

oDistance—Specifies the distance as a radius within which input sample points will be used to perform the interpolation.

The value of the radius is expressed in map units. The default radius is five times the cell size of the output raster.

oMinimum number of points—An integer defining the minimum number of points to be used for interpolation. The default value is 0.

If the required number of points is not found within the specified distance, the search distance will be increased until the specified minimum number of points is found.

When the search radius needs to be increased it is done so until the Minimum number of points fall within that radius, or the extent of the radius crosses the lower (southern) and/or upper (northern) extent of the output raster. NoData is assigned to all locations that do not satisfy the above condition.

7. Input barrier polyline features (optional)

Polyline features to be used as a break or limit in searching for the input sample points.

Kriging

How to use Kriging Tool in ArcToolbox ArcMap ArcGIS ??

Kriging Tool

Kriging Tool, Raster Interpolation Toolset, 3D Analyst Toolbox

Kriging

Interpolates a raster surface from points using kriging.

1. Input point features

The input point features containing the z-values to be interpolated into a surface raster.

2. Z value field

The field that holds a height or magnitude value for each point.

This can be a numeric field or the Shape field if the input point features contain z-values.

3. Output surface raster

The output interpolated surface raster.

It is always a floating-point raster.

4. Semivariogram properties

The Semivariogram model to be used. There are two methods for kriging: Ordinary and Universal.

Ordinary kriging can use the following semivariogram models:

· Spherical—Spherical semivariogram model. This is the default.

· Circular—Circular semivariogram model.

· Exponential—Exponential semivariogram model.

· Gaussian—Gaussian or normal distribution semivariogram model.

· Linear—Linear semivariogram model with a sill.

Universal kriging can use the following semivariogram models:

· Linear with Linear drift—Universal Kriging with linear drift.

· Linear with Quadratic drift—Universal Kriging with quadratic drift.

There are options available via the Advanced Parameters dialog box. These parameters are:

· Lag size—The default is the output raster cell size.

· Major range—Represents a distance beyond which there is little or no correlation.

· Partial sill—The difference between the nugget and the sill.

· Nugget—Represents the error and variation at spatial scales too fine to detect. The nugget effect is seen as a discontinuity at the origin.

5. Output cell size (optional)

The cell size of the output raster that will be created.

This parameter can be defined by a numeric value or obtained from an existing raster dataset. If the cell size hasn't been explicitly specified as the parameter value, the environment cell size value will be used if specified; otherwise, additional rules will be used to calculate it from the other inputs. See the usage for more detail.

6. Search radius (optional)

Defines which of the input points will be used to interpolate the value for each cell in the output raster.

There are two options: Variable and Fixed. Variable is the default.

· Variable

Uses a variable search radius in order to find a specified number of input sample points for the interpolation.

oNumber of points—An integer value specifying the number of nearest input sample points to be used to perform interpolation. The default is 12 points.

oMaximum distance—Specifies the distance, in map units, by which to limit the search for the nearest input sample points. The default value is the length of the extent's diagonal.

· Fixed

Uses a specified fixed distance within which all input points will be used for the interpolation.

oDistance—Specifies the distance as a radius within which input sample points will be used to perform the interpolation.

The value of the radius is expressed in map units. The default radius is five times the cell size of the output raster.

oMinimum number of points—An integer defining the minimum number of points to be used for interpolation. The default value is 0.

If the required number of points is not found within the specified distance, the search distance will be increased until the specified minimum number of points is found.

When the search radius needs to be increased it is done so until the Minimum number of points fall within that radius, or the extent of the radius crosses the lower (southern) and/or upper (northern) extent of the output raster. NoData is assigned to all locations that do not satisfy the above condition.

7. Output variance of prediction raster (optional)

Optional output raster where each cell contains the predicted variance values for that location.