How does Assign Images works ?

[PROBERT1968]

My  question here was to ask about this that was not found  in the manual when I am searching for it.

So my question is how does this assign to image works ?  This is done when you build an orthomosaic .  You have to use polygon to draw around on specific area you want.  So when you do that
you right click and assign to Image . It brings you up a dialog box and in it has a list the rank number.

How  does this work ? and why would it give you 1,2,3 ?

BTW, where does this  came from ?

Does the rank came from the Photo Pane that uses the rank order ?

Please help me understand this .

Thanks

[Alexey Pasumansky]

Hello PROBERT1968,

The rank in Assign Images dialog is based on the internal Metashape metric that estimates how good is the image for the given orthomosaic patch. It consideres the distance from camera to the area of interest, distance of the area of interest from the image center, angle between the camera normal and surface normals and etc.

If you do not agree with the suggested #1 image you can choose the most appropriate image from the list to be assigned to the drawn polygonal patch.

[PROBERT1968]

Thank you for your kindly repsond...

Another question ...  I am confuse you mention  polygonal patch, do you mean "Draw Patch" in the Ortho mode ? I use Draw Polygon instead and will that make any difference ?

What about using  the markers ? Will that rank the assign image ?

[Costas]

Hello PROBERT1968,

Using "Draw Polygon" and/or "Draw Patch" is essentially the same. There is only a slight difference. In "Draw Patch" the best fit image will be applied automatically.
Note: You can still choose to assign a different picture than the "best fit".

Description from the Help Documentation:

"If the Assign image operation should be repeated several times, it is recommended to use  Draw Patch tool available from the Ortho menu or with a corresponding Toolbar button of the Ortho view menu. In this case it will still be required to draw polygons as in the procedure above, but the best fit image will be assigned automatically, being selected with respect to the first drawn vertex of the patch."

In any case after assigning the photos you want, always remember to use the "Update Orthomosaic".

[JMR]

but the best fit image will be assigned automatically

There is something that should be clarified. This automation takes for reference the location of first vertex you enter when you draw the patch.
I think developers should rather offer a few best choices according to:
1. Camera closer to the centre of mass of the patch (no to the first vertex), and closest to the principal point of suitable cameras.
2. Best orientation. best fit plane on patch vertices could be used to sort photos according to angle with respect to the patch.
3. Content awareness. In a more advanced approach, the software should be able to skip photos with pixels that are inconsistent between overlapping photos. That would help to remove moving vehicles, for example. Actually I wonder IF Such smart filter could not be used during orthomosaic creation as well to automatically remove people, cars, birds, branches, etc.

Regards
José Martínez
GEOBIT / ACCUPIXEL

[James]

I thought that this was what the 'Enable ghosting filter' option was supposed to do. I haven't tried it though.

3. Content awareness. In a more advanced approach, the software should be able to skip photos with pixels that are inconsistent between overlapping photos. That would help to remove moving vehicles, for example. Actually I wonder IF Such smart filter could not be used during orthomosaic creation as well to automatically remove people, cars, birds, branches, etc.

[Alexey Pasumansky]

Yes, James, you are right. Ghosting filter enabled for the orthomosaic generation should allow for removal of unwanted moving objects. However, it requires quite accurate and detailed surface to be used for the orthomosaic, otherwise the result will be affected.

[PROBERT1968]

Thank you everyone for the feedback !

[PROBERT1968]

I wanted to respond to  @Coatas for point me out on Draw Patch. Thank you !  i took a look at it and see what it does...

However, I do have a question.  Should I assign which image first and then use the Draw Patch ?

I tried both ways and I can see the difference..

So which one is a benefit ?

[Costas]

Hello Robert1968,

I'm not an expert in this matter (i may be wrong) but i only use this feature if i need to remove an object from an Orthomosaic or if i want to make some blurry areas in Orthomosaics more clear by selecting a better image.

From what i understand the only difference between "Draw Polygon" and "Draw Patch" is that the second automatically chooses the best fit picture. Essentially you may only save a few clicks and time when you have a lot of editing to do.


To summarize:

Lets say that you have to do 20 edits in a big Orthomosaic.

Method A
Draw Polygon --> Assign image. (you do this for every polygon you create)

Method B
Draw Patch and see the result. Only if not happy with the result, right click and Assign an image you like. (No need to draw another simple polygon.)

I personally mostly use the second method because sometimes it saves me time when i have a lot of editing to do.

[PROBERT1968]

Thank you.  I will go over this when I have the time to work on my projects.



One more thing Everyone thank you for bringing it up and discussions...

Good to know.