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Author Topic: Align/snap model and region to axes  (Read 3237 times)

Lesca

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Align/snap model and region to axes
« on: March 03, 2021, 02:03:45 PM »
Hello all!

I've done some reasearch on this issue before, and it seems to have been a problem for some users for quite some time, but wasn't really addressed or fixed until now. I'm also not sure if there is a Phython solution to this problem. If so, please let me know. A user-friendly integration to the ui would then of course very good!

In my experience processing hundreds of scans in Photoscan/Metashape, there is not a single model that I remember that was correctly aligned.
It is frustrating and time consuming as well as unprecise to do this by hand. I've seen Meshlab and Cura be able to do this by selecting a bunch of faces and automatically aligning them to the axes. Capturing Reality seems to have had this process built in for years (but I don't use their software for various reasons).

Right now, I'm manually using a method similar to this older forum post: https://www.agisoft.com/forum/index.php?topic=5463.0
Use the below technique to orient your scans upright. To set a real world scale and/or specific location (such as 0,0,0) within photoscan you will need the pro version so that you can set markers/scalebars, otherwise you will have to do it externally.

You can use Rotate Object tool for unrefrenced chunks to change their orientation in the coordinate system.

My preferred method of using it is:

1. hit numpad 7 to go to top view
2. then invoke the rotate object tool to rotate the model to a top view.
3. hit space bar to return to 'normal' navigation mode
4. hit numpad 1 to go to front view
5. hit space again to return to rotate object mode and fine tune the rotation in front view
6. hit space to return to normal nav mode again
7. hit numpad 3 to get a side view
8. hit space to get back to rotate object mode and further fine tune the rotation if required
9. hit space to get back to normal navigation mode
10. hit numpad 7, 1 and 3 in sequence to check the model is aligned and repeat the above if necessary.

I would therefore like to see a semi-automatic or automatic process for aligning the model and region on the axes.

I understand that sometimes it can be difficult to guess the alignment of images taken upside down or rotated 90°.
But in my case, I often use the turntable where the orientation is very clear based on the images. Even using the images as a reference (rather than the sparse point cloud) for orientation would be sufficient for me. But a sophisticated solution that can be applied to the mesh or dense point would be greatly appreciated!

Also a function to rotate the model in e.g. 90° steps while holding down e.g. the ALT key would be great!

Thanks a lot in advance!
Metashape 1.7.1, Ryzen 3950x, Vega VII + Vega 64, MacOS 10.14.6 (Hackintosh/Ryzentosh), 64 GB DDR4 3200 MHz RAM

Steve003

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Re: Align/snap model and region to axes
« Reply #1 on: October 12, 2021, 03:33:47 PM »
Hi,
 I cannot believe just you and I wish to align a model to the grid, so when I use top view I see its top, and its squared up correctly not at some silly angle.
in 3D we always make objects ALIGNED to a grid, that we have to have them on zero gravity so it would seem is causing me problems right from the outset.

numpad 7 for top view ? my numpad has 8 at middle top  but that rotates so I guess 7 will have to be top.

I hit 7 and it says orthographic but not TOP which is what we need to see and know we are in top view. I rotate as best the sphere allows,
space bar and numpad 1 for front (key marked END , side view would have been more logical !)

numpad 3 for side (key marked PgDn) and its leaning over badly, but there is no grid to align it to. Show\hide items and grid icon is already 'on' I cant turn grid on any more and its not visible.

WE NEED GRID SURELY TO ALIGN TO , but these alignment steps are without grid.
How do we get grid to show when using them ?

Done as best as poss with no grid.
Go into perspective view, and try to tumble the view and only the region box rotates, I cant tumble the object.

How does one tumble the object ?

The basic 3D viewing and alignment experience is not happening for me,  I cant even see a youtube on this fundamental part of using Metashape, so no video help on it all all to be had, so what am I doing wrong, how is it done with grid to align to, AND with rotate sphere aligned up orthographically and how does one rotate tumble in perspective mode ?

Someone needs to do a video on the basics of viewing as its crucial, I am sure others must hit this issue ?
 :( :-\
Steve

Eric Baird

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Re: Align/snap model and region to axes
« Reply #2 on: October 17, 2021, 05:13:28 PM »
It'd also be useful, when one has successfully aligned the model with the grid, to be able to snap the bounding box to align with the grid.

One often wants the bounding box to line up neatly with the model to provide a strip of lawn/pavement/etc surrounding a building for context, and having gone to the trouble of lining the building up with the grid on x,y,z, it seems tedious to have to then manually align the bounding box up with x, y, z, too. It'd be faster to just snap the box to the grid and then adjust the size handles to suit.

CheeseAndJamSandwich

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Re: Align/snap model and region to axes
« Reply #3 on: October 17, 2021, 05:39:43 PM »
You're not alone.
I posted this a few days ago...
https://www.agisoft.com/forum/index.php?topic=13837.0

If we could get a very basic reference system in the Standard version, allowing us to put down a minimum of 3 markers, control points, that we know the positions of, then the models would snap to the exact correct orientation and scale.
Leave out all the georeferencing stuff the the big boys use for scanning mine sites, etc. that needs Metashape Professional for...

So for your turntable work, you could put down 3 point around the rim of the turntable, that you know the x,y coordinates for, in milometers perhaps, and then zet z to zero.  This make the model's orientation and scale perfect.

Every time i create a model, which is derived from gopro images, underwater, the model is never, ever in the correct orientation or the correct scale... and i have to do the same workaround procedure to fix it.

It would be awesome to get some basic tools to make this work.