How to import and mark Manual Tie Points (MTPs)

 
Video: Watch the instructional video about Manual Tie Points: here.

An Automatic Tie Point (ATP) is a 3D point corresponding to a keypoint that is automatically detected and matched in the images.
A Manual Tie Point (MTP) is a 3D point corresponding to a keypoint that is marked (clicked) by the user in the images. A typical use is for assessing and improving the reconstruction accuracy.

The MTPs can be imported into the software using one of the following methods:

Using the rayCloud

The Manual Tie Points can be introduced in a project using the rayCloud, only after step 1. Initial Processing has been completed.

 

1. On the menu bar click View > rayCloud.
2. In the 3D view, select a point in the area where the MTP has to be added.

 
Note:
  • On the right sidebar, on the Images section, all the images, in which the clicked (selected) point is visible, appear.
  • A green cross appears on all images that symbolizes the projected position of the selected point. Some images (at least two) have also an orange cross, which indicates the position on which this point was found in order to compute its 3D position.

automatic_tie_points.png

3. Click tie_point_add.png New Tie Point to insert a new Manual Tie Point.

new_tie_point.png

4. A new MTP and its information is added on the right sidebar, in the Selection section.
5. (optional) Change the name: Double click the Label cell of the Manual Tie Point and type the desired name.
6. Navigate on each image to find the exact location of the Manual Tie Point:

    • Zoom in: Moving the mouse scroll wheel forwards.
    • Zoom out: Moving the mouse scroll wheel backwards.
    • Pan: Using the mouse left clicking.
    • Change the size of the images: Move the slider of the Image Size bar.

7. Mark the Manual Tie Point on at least two images using the left mouse click.

 
Note:
  • When marking MTPs on the images, each mark is used to compute a new 3D point. At least two images need to be marked in order to compute the estimated 3D position of the point. The estimated 3D point is reprojected on all the images in which it might be visible.
  • The clicked position appears with a yellow cross and circle. The size of the yellow circle indicates the zoom level in which the marking has been done. Points that have been marked on a high zoom level are taken more into account than points that have been marked on a lower zoom level.
  • After clicking on 2 images, a green cross appears on all images. The green cross represents the reprojection of the estimated 3D point on all images, and is calculated (after having marked 2 images) according to the clicks already made for the Manual Tie Point.
  • After clicking on 2 images, an outlier is indicated with a pink circle when the point is erroneously marked on other images. Outliers do not influence the resulted reconstruction.
 
Tip: To delete a mark (yellow cross) that has been wrongly clicked, hover the mouse over the image and press the key Delete.

8. Check the images that have not been marked:

    • If the green cross corresponds to the correct Manual Tie Point position: Then there is no need to mark the point on more images.
    • If the green cross does not correspond to the correct Manual Tie Point position: Click on more images. Every time you click on one image, the green cross approaches more the correct place.

9. (optional) Click Automatic Marking to automatically mark the 3D point in the images that have not been marked.
10. When the green cross is at the correct place in most images, click Apply.

rayCloud_new_tie_point_after_apply.png
11. Repeat steps 2 to 10 to add more Manual Tie Points.
12. When all Manual Tie Points are marked on the images, click Process > Reoptimize. This reoptimizes the reconstruction using the Manual Tie Points.

 
Note: For more information about the Reoptimize option: 202557809.

13. (optional) To generate the new Quality Report, click Process > Generate Quality Report.

Using the GCP/MTP Manager

The Manual Tie Points can be introduced in a project using the GCP/MTP Manager before running step 1. Initial Processing.

 

Adding Manual Tie points in the GCP/MTP Manager:

1. On the Menu bar, click Project > GCP/MTP Manager...
2. On the GCP/MTP Manager, under the section GCP/MTP Table, click Add Point.

 
Note: A new point is added in the GCP/MTP Table. It is defined by default as Manual Tie Point (Type column) and it is named by default mtp1. When adding more Manual Tie Points, they will be named mtp2, mtp3, etc.

3. (optional) Change the name: Double click the Label cell of the Manual Tie Point and type the desired name.
4. Repeat steps 1 to 3 for the other Manual Tie Points. For more information about the GCP/MTP Table properties: 202557919.

 

Marking the added Manual Tie Point in the Basic GCP/MTP Editor:

1. On the GCP/MTP Manager, under the section GCP/MTP Editor, click Basic Editor...,  the Basic GCP/MTP Editor appears: 

gcp_mtp_editor.png

2. In the table, click on the Manual Tie Point to be marked.
3. Under the Images section, select the image in which the Manual Tie Point should be marked. After the selection, the image is displayed in the Preview section.
4. Navigate in the image by: 

    • Zoom in: Moving the mouse scroll wheel forwards.
    • Zoom out: Moving the mouse scroll wheel backwards.
    • Pan: Using the mouse left click.
    • Zoom in quickly on a specific point in the image: point with the mouse the point and press the Alt key. When the key is released, the view returns to the last zoom level.
    • Zoom out to preview the zero zoom level: Press the Shift key. When the key is released, the view returns to the last zoom level.

5. Left click on the image to mark the point.
6. (optional) click gcp_editor_remove_button2.png to remove a mark.
7. On the Images section, select the next image on which the Manual Tie Point will be marked.

 
Note: A Manual Tie Point does not need to be identified / marked on all images in which it appears. Ideally, mark a Manual Tie Point in 3 to 8 images (the minimum number of images is 2). The Quality Report indicates after Initial Processing if it is needed to mark the Manual Tie Point in more images.

8. Repeat the above steps 2-7 to mark other Manual Tie Points.
9. Click OK.

 

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6 comments

  • Steve Hall

    The 'See more' buttons do not work

  • Daniel (Pix4D)

    Hello Steve,

    What internet browser are you using? I just checked and it works on my side.

    Thank you for reporting it.

  • Christian Herrmann

    @Daniel   Hallo,

    I have exported already measured mtp`s to a external file in *.shp and*.dxf format by clicking right mouse button at the MENU---Tie Points Tab.
    After this, i deleted the mtps from the list. When I tried to Import these mtps again, i can't find a way for an import. Please show me a way to import these mtps again.

    Thanks forward

  • Daniel (Pix4D)

    Hallo Christian,

    The only way to import/export MTPS is through the GCP/MTP manager where you import the coordinates.

    If you drew a line and you exported it as DXF and SHP, there is no way to import it again if you already deleted it.

    Regards.

  • Christian Herrmann

    That doesn`t work because the available export file formats for mtp`s is *.dxf *.shp and *.dgn
    If i want to import the mtp`s again through the GCP editor, so i just can use *.csv
    How should it work? I don`t want to import lines!

  • Daniel (Pix4D)

    Hello again,

    You can import/export the GCP measurement through the GCP editor in .csv or .txt:

    If you have exported the points from the RayCloud as DXF or SHP, you cannot import them again.

    Regards.

     

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