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Autopano - Common cases that don't stitch automatically - Repetitive patterns


Issue

In case of repetitive patterns, Autopano would have difficulties to find control points on the right places, as details on an image can be the same on 2, 3 or 10 images away.
There is several solutions to achieve the panoramas, mostly depending about the shooting and the hardware used.


Example 1: Rubik's cube scene

The shot

6+Z+N shot


This is the typical shooting case when working on virtual tours: 8 fisheye photos, shot in 6 + Z + N mode (6 horizontal photos, one photo on the Zenith and one photo on the Nadir). 
In this type of shot, the mesh should look like this:

Ideal meshing
  • Image 1 is linked to 2, 6 then to 7 and 8.
  • Image 2 is linked to images 1, 3, 7 and 8
  • Image 3 is linked to images 2, 4, 7 and 8
  • Image 4 is linked to images 3, 5, 7 and 8
  • Image 5 is linked to images 4, 6, 7 and 8
  • Image 6 is linked to images 5, 1, 7 and 8
  • Image 7 is linked to images 1, 2, 3, 4, 5, and 6
  • Image 8 is linked to images 1, 2, 3, 4, 5, and 6


Based on this principle, the idea is to let Autopano calculate all the links, remove false links and re-optmize the panorama. 3 quick steps to obtain a perfect result!


Step 1: Detection

After importing the photos in Autopano (and checking the shooting information), open the Group Settings and select the Optimization tab.
Activate the manual mode by checking the first checkbox and uncheck all options keeping only the Local approach option checked:
TIP.png During a local approach, good links will be less affected by the bad links than in any other step.


Advanced settings, Optimization tab


Confirm (OK) and launch the detection:


Panorama obtained


The RMS of the stitching is very poor (62.29) but this is not important for the moment.


Step 2: Cleaning the links

Open the Panorama editor, then the Control Points editor to check the links mesh:


maillage obtenu


It is clear that the mesh doesn't correspond at all to the ideal mesh shown above.
Autopano has calculated all the links without removing those that may be considered bad.
Such settings used for the group allow to retain all the links and all the control points.
Now you only need to remove the bad links using the links list from the control points editor, to obtain a mesh similar to the ideal one:


Here is the list before cleaning. One can see the list of wrong links in the upper section (e.g. image 1 linked to images 3, 4 and 5):


List containing wrong links


After cleaning (removal of wrong links), the list looks like this (identical to the ideal grid):

Cleaned list
  • Image 1 is linked to 2, 6 (because 360°) then to 7 and 8.
  • Image 2 is linked to images 1, 3, 7 and 8
  • Image 3 is linked to images 2, 4, 7 and 8
  • Image 4 is linked to images 3, 5, 7 and 8
  • Image 5 is linked to images 4, 6, 7 and 8
  • Image 6 is linked to images 5, 1, 7 and 8
  • Image 7 is linked to images 1, 2, 3, 4, 5, and 6
  • Image 8 is linked to images 1, 2, 3, 4, 5, and 6


Ideal meshing


Step 3: Optimization

Now that the mesh is clean, it is necessary to re-optimize the panorama. Before carrying out this operation, a slight modification of the optimization settings is required.
Open the Steps tab and check back the optimization steps 2, 3, 5 and enable the the bad points clean:

Control Points editor settings


Then run a complete optimization of the panorama (using the complete optimization icon):

Result


The stitching is excellent (RMS of 2.62 with 994 control points). The last thing to be done is to export the panorama!


Example 2: Chapel scene

The shot

In this example, the shot does not contain the Nadir image, except that point, the shooting layout is the same than the first example, 6 images at 0° and one Zenith image.

6+Z shot


Step 1: Detection

As in example 1, import the photos, check the shooting information and open the Group Settings in the Optimization tab.
Activate the manual mode by checking the first checkbox and uncheck all options keeping only the Local approach option checked:

Advanced settings, Optimization tab


Validate (OK) and launch the detection:

Panorama obtained


The RMS for the stitching is also very poor (39.95) but this is not important.


Step 2: Cleaning the links

Open the Panorama editor, then the Control Points editor in order to check the mesh: 


Mesh obtained


As in example 1, the mesh does not match the ideal one.
It is now necessary to remove the bad links using the links list from the control points editor, to obtain a proper mesh:


Here is the list before cleaning containing the wrong links (1 linked to 4, for example):


List containing wrong links


... List after cleaning :

Liste cleaned


Step 3: Optimization

Open the Steps tab and check back the optimization steps 2, 3, 5 and enable the the bad points clean:

Control Points editor settings


Confirm (OK), then run a full optimization of the panorama (using the Optimization icon):

Result after optimization


The stitching is perfect. The panorama can now be exported!


Example 3: Facade shot hand held

The shot

This panorama was shot hand held with multiple viewpoints, ie the photographer moved parallely to the facade to be able to shoot it from a comfortable distance.
This is a specific case as shots were done with a thermic camera, and there is no EXIF on the images.
Thanks to Christophe ACHTE for his images (all rights reserved).

Hand held shooting


Step 1: Detection

Import the images, as stated above, we can confirm the EXIF are not present. Then directly launch the detection. Here is what we get:

Detection


Note: All the images are detected in this example, but that could be not the case, if so, it would be necessary to force the images via the Detection options of the Group Settings.


Let's check the panorama, here is the linking found at very first attempt:

Linking


Images are all linked but there is no logical mesh for now, images are containing too many similarities.


Step 2: Moving the images

Depending on the information we have about this shooting (hand held, multiple viewpoints, illogical shooting layout, repetitive patterns on all the images), there is no full automatic way to achieve the panorama.
A manual processing is necessary, we would have to move each image at its right place. In this case, it would be also necessary to know how the shooting was done and use the index of the images to do it easily.
Activate the Move tool and select the option to move individual images separately (Picture):


Move tool, Picture option


And here is the result of the manual moving, this looks like much a building now:

Manual move processing


Then I just removed some useless images that wouldn't bring any interesting aspect on the panorama:

Images removal


Step 3: Cleaning the links

Have a look now to the linking. Most of the links are wrong:

Current linking


Here is 2 links highlighted to illustrate the mistake, the left side image (29) is linked to the right side image (7) and the image 18 to the image 9:

Wrong links


Enable the Control Points tool and use the Links filtering option, hit the icon to remove all the links of the panorama (as only a few of them are ok, there is no reason to keep them in this case):

Links filtering


Here is what we get:

Links cleaned


Step 4: Creating new proper links

Now the idea is to calculate and found control points on images, as there is a quite large quantity of images, we would not define areas to find points on each pair of image.
We will use the Geometry analysis there. Do a right click on the image and select Local geometry analysis:

Geometry analysis


The process result:

Result


And let's continue with the other images:

Geometry analysis

Result


Until we finally get this:

Final geometry analysis


The mesh looks nice and logical, process to a Quick optimization to validate the links:

Optimization


Here is the optimization result:

Linking after optimization


Now it simply remains to improve the few bad links and set the Scopes to improve the whole stitching (multiple viewpoints, focal calculation, distortions, offsets…) to give this:

Final optimization


Finally, use the vertical lines tool or the Move tool to straighten the panorama and render it!
















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