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Compute Control Points

Summary

Computes the control points between the mosaic dataset and the reference image. The control points can then be used in conjunction with tie points to compute the adjustments for the mosaic dataset.

Usage

  • If you want accurate control point results, the High tolerance option for the Similarity parameter is recommended.

  • The control points can be combined with tie points, using the Append Control Points tool.

  • The control points and tie points are then used within the Compute Block Adjustment tool.

  • If you have many items within your mosaic dataset, the Output Image Features parameter should not be specified; otherwise, your result can take a long time to calculate.

Syntax

ComputeControlPoints_management (in_mosaic_dataset, in_reference_images, out_control_points, {similarity}, {out_image_feature_points}, density, distribution, area_of_interest, {location_accuracy})
ParameterExplanationData Type
in_mosaic_dataset

The input mosaic dataset that will be used to create control points.

Mosaic Dataset; Mosaic Layer
in_reference_images

The reference images that will be used to create control points for your mosaic dataset. If you have multiple images, create a mosaic dataset from the images and use the mosaic dataset as the reference.

Raster Layer; Raster Dataset; Image Service; MapServer; WMS Map; Mosaic Layer; Internet Tiled Layer; Map Server Layer
out_control_points

The output control point table. This table will contain the control points that were created.

Feature Class
similarity
(Optional)

Choose the tolerance level for your control point matching.

  • LOWThe similarity tolerance for finding control points will be low. This option will produce the most control points, but some may have a higher level of error.
  • MEDIUMThe similarity tolerance for finding control points will be medium.
  • HIGHThe similarity tolerance for finding control points will be high. This option will produce the least number of control points, but each matching pair will have a lower level of error. This is the default.
String
out_image_feature_points
(Optional)

The output image feature points table. This will be saved as a polygon feature class. This output can be quite large.

Feature Class
density

Set the number of tie points to be created.

  • LOWSet the density of points to be low. This will create the fewest number of tie points.
  • MEDIUMSet the density of points to be medium. This will create a moderate number of points.
  • HIGHSet the density of points to be high. This will create the highest number of points.
String
distribution

Choose to create a set of points with a regular or random distribution.

  • RANDOMRandomly generated points are better for overlapping areas with irregular shapes.
  • REGULARRegular generates points based on a fixed pattern and uses the point density to determine how frequently to create points.
String
area_of_interest

Limit the area in which tie points are generated to only this polygon feature class.

Feature Layer
location_accuracy
(Optional)

Choose the keyword that best describes the accuracy of your imagery.

  • LOWImages have a large shift and a large rotation (> 5 degrees).The SIFT algorithm will be used in the point matching computation.
  • MEDIUMImages have a medium shift and a small rotation (<5 degrees).The Harris algorithm will be used in the point matching computation.
  • HIGHImages have a small shift and a small rotation.The Harris algorithm will be used in the point matching computation.
String

Code sample

ComputeControlPoints example 1 (Python window)

This is a Python sample for the ComputeControlPoints tool.

import arcpy
arcpy.ComputeControlPoints_management("c:/block/BD.gdb/redQB", 
     "c:/block/BD.gdb/redQB_tiePoints", "HIGH",
     "c:/block/BD.gdb/redQB_mask", "c:/block/BD.gdb/redQB_imgFeatures")
ComputeControlPoints example 2 (stand-alone script)

This is a stand-alone script sample for the ComputeControlPoints tool.

#compute control points

import arcpy
arcpy.env.workspace = "c:/workspace"

#compute control points using a mask 
mdName = "BD.gdb/redlandsQB"
in_mask = "BD.gdb/redlandsQB_mask"
out_controlPoint = "BD.gdb/redlandsQB_tiePoints"
out_imageFeature = "BD.gdb/redlandsQB_imageFeatures"

arcpy.ComputeControlPoints_management(mdName, out_controlPoint, 
     "HIGH", in_mask, out_imageFeature)

Licensing information

  • ArcGIS Desktop Basic: No
  • ArcGIS Desktop Standard: Yes
  • ArcGIS Desktop Advanced: Yes