FilterTiePointsByFundamentalMatrix Task

This task uses the fundamental matrix to constrain the location of the tie points.

The following diagram shows where this task belongs within an image-to-image registration workflow:

References:

Jin, Xiaoying. ENVI automated image registration solutions. NV5 Geospatial Solutions, Inc. whitepaper (2017). ENVI automated image registration solutions can be downloaded from our website.

Jin, Xiaoying, and Robert Schafer. Method and system for automatic registration of images. Exelis, Inc., assignee; now owned by NV5 Global, Inc. U.S. Patent No. 9,245,201 (issued January 26, 2016).

Example

This example uses sample images from the Image Registration tutorial. The files are available from our ENVI Tutorials web page. Click the Image Registration link to download the .zip file to your machine, then unzip the files. Update the file references in the example with the correct locations.

; Start the application

e = ENVI()

; Open input rasters

File1 = 'quickbird_2.4m.dat'

File2 = 'ikonos_4.0m.dat'

Raster1 = e.OpenRaster(File1)

Raster2 = e.OpenRaster(File2)

; Get the auto tie point generation task from the catalog of ENVITasks

Task = ENVITask('GenerateTiePointsByCrossCorrelation')

; Define inputs

Task.INPUT_RASTER1 = Raster1

Task.INPUT_RASTER2 = Raster2

; Run the task

Task.Execute

; Get the output tie points

TiePoints = Task.OUTPUT_TIEPOINTS

; Get the tie point filter task from the catalog of ENVITasks

FilterTask = ENVITask('FilterTiePointsByFundamentalMatrix')

; Define inputs

FilterTask.INPUT_TIEPOINTS = TiePoints

; Run the task

FilterTask.Execute

; Get the output tie points

TiePoints2 = FilterTask.OUTPUT_TIEPOINTS

; Get the image-to-image registration task from the catalog of ENVITasks

RegistrationTask = ENVITask('ImageToImageRegistration')

; Define inputs

RegistrationTask.INPUT_TIEPOINTS = TiePoints2

RegistrationTask.WARPING = 'Triangulation'

; Run the task

RegistrationTask.Execute

; Get the output raster

WarpedRaster = RegistrationTask.OUTPUT_RASTER

; Get the collection of data objects currently available in the Data Manager

DataColl = e.Data

; Add the output to the Data Manager

DataColl.Add, WarpedRaster

; Display the input rasters

View = e.GetView()

Layer1 = View.CreateLayer(Raster1)

Layer2 = View.CreateLayer(Raster2)

; Display the result

Layer3 = View.CreateLayer(WarpedRaster)

Syntax

Result = ENVITask('FilterTiePointsByFundamentalMatrix')

Input parameters (Set, Get): INPUT_TIEPOINTS, OUTPUT_TIEPOINTS_URI, REPROJECTION_ERROR_THRESHOLD

Output parameters (Get only): OUTPUT_TIEPOINTS

Parameters marked as "Set" are those that you can set to specific values. You can also retrieve their current values any time. Parameters marked as "Get" are those whose values you can retrieve but not set.

Input Parameters

INPUT_TIEPOINTS (optional)

This is a reference to the ENVITiePointSet object generated from the GenerateTiePointsByCrossCorrelation or GenerateTiePointsByMutualInformation task.

OUTPUT_TIEPOINTS_URI (optional)

Specify a string with the fully qualified path and filename for OUTPUT_TIEPOINTS.

REPROJECTION_ERROR_THRESHOLD (optional)

Specify the reprojection error threshold to use. It is defined as the perpendicular distance (in pixel units) of a point in one image from its corresponding epipolar line computed from a point in another image. The default value is 10.0.