Image Correlation with PIX4Dmapper

PIX4Dmapper cannot do the automatic image correlation for circles, but it is possible:

Using the Pix4Dtagger tool
Using external software

Using the Pix4Dtagger tool

It uses some specific images that can be printed and placed on site, then the application will create directly the manual tie points and mark them in the images where they are present and they will be already included within a .p4d project file, then they can be as well be converted into GCPs if a GCP was used to measure the specific images.

The advantage is that as each image is different, then it is possible to place the coordinates via Pix4Dtagger for each one of them directly.

For more information and to download the Pix4Dtagger tool: Using Pix4Dtagger - automatic target recognition.

Using external software

For example, using circles as GCP markers:

1. Create a project and run the step 1 without include the GCPs or manual tie points.
2. Import the GCPs coordinates: How to import and mark ground control points (GCPs).
3. Use external software (MatLab or another) to generate the GCPs and manual tie points marks in order to locate the center of the circles.
4. Edit the results in order to create a bingo file with the following format: What does the Bingo File that is generated when clicking on Export Marks... contain?.
5. Import the marks: Menu Project > GCP / MTP Manager... > GCP / MTP Table > Import / Export Marks....

Note: (optional) If a point was not previously imported in step 2, it will be imported as manual tie point, double click on it in order to change the status to 3D GCP, 2D GCP or Check point.

6. Reoptimize the project.

Another option is:

1. Create a project and run the step 1 without include the GCPs or manual tie points.
2. Use external software (MatLab or another) to generate the GCPs and manual tie points marks in order to locate the center of the circles.
3. Edit the results in order to create a bingo file with the following format: What does the Bingo File that is generated when clicking on Export Marks... contain?.
4. Import the marks: Menu Project > GCP / MTP Manager... > GCP / MTP Table > Import / Export Marks....

Note: Since no point was imported, all of them will be imported as manual tie points, double click on them and change the status to 3D GCP, 2D GCP or Check point: GCP / Manual Tie Point Table.

5. Import the GCPs coordinates: How to import and mark ground control points (GCPs).
6. Reoptimize the project.