How to get rid of bad control points

[Paul Chubbuck]

I have a pano with fast moving cloud.  PTGui is finding many control points in the sky, which is probably the cause of stitching problems on the horizon.  I have gone through and deleted all of those points, but as soon as I take the next step of "Align Images", PTGui re-identifies those same bad control points.

How can I make it leave those points unselected?

Thanks,

Paul

[Paul Chubbuck]

Can these files be stitched well? 

https://drive.google.com/folderview?id=0BxmzkJ9EXQwsR1F6RnBxUlhtQ2c&usp=sharing

I have not been able to get rid of bad discontinuities on the horizon, but there's a lot I don't know about PTGui.

Paul

[John Houghton]

On Sunday, July 10, 2016 at 4:55:04 AM UTC+1, Paul Chubbuck wrote:

Can these files be stitched well? 

https://drive.google.com/folderview?id=0BxmzkJ9EXQwsR1F6RnBxUlhtQ2c&usp=sharing

I have not been able to get rid of bad discontinuities on the horizon, but there's a lot I don't know about PTGui.

You should not run Align Images more than once, unless you really know what you are doing. You can get a good horizon by first stitching only the single horizon row, with control points only in the far distance where parallax effects effectively cease.  The other images can then be added, control points generated and optimized into alignment using the optimizer in Advanced mode and unchecking all the y,p,r paramaters of the horizon row so they cannot shift out of alignment.  I got this result:  https://www.sendspace.com/file/zviuaw .  Out of interest, I tried ICE on these images and got a very poor result.

John

[Paul Chubbuck]

Wow!  Very nicely done, John.

I'm afraid you are going over my head with the explanation though.  I don't know what you mean by "The other images can then be added, control points generated and optimized into alignment using the optimizer in Advanced mode and unchecking all the y,p,r paramaters of the horizon row so they cannot shift out of alignment" or "ICE".   I will try it and see if I can make sense of your instructions.  If not, I may be back for a little more direction.

In any case, thank you.

Paul

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[Paul Chubbuck]

Clarification.  I do understand what parallax is and its relevance to stitching.  I just don't understand how to do what you refer to.

[Paul Chubbuck]

I successfully stitched the horizon row with no significant stitching errors.  And I see now what you meant by unchecking the YPR.  But I am not clear on the steps to add the other images.

[Paul Chubbuck]

Something must be wrong in the order I am doing things because after unchecking YPR for those horizon images, and loading the rest of the images, then I click "Align" and "Create Panorama" and the same discontinuities re-appear, which were not there after stitching the horizon images only.

Paul

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[Paul Chubbuck]

On closer examination of my horizon-shots-only stitching, many of the discontinuities are actually still there, unlike in your pano from my images.  So I'm clearly not getting the technique.  Any further help would be much appreciated.

Thanks,

Paul 

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[John Houghton]

On Sunday, July 10, 2016 at 4:04:24 PM UTC+1, Paul Chubbuck wrote:

On closer examination of my horizon-shots-only stitching, many of the discontinuities are actually still there, unlike in your pano from my images.  So I'm clearly not getting the technique.  Any further help would be much appreciated.

Paul, to get the horizon row properly stitched, you can simply load in the 10 images and start by using Align Images (once only) to align them roughly.  Then comes the laborious part:  switch into Advanced mode, via the button on the right of the Project Assistant.  Select the Control points tab, and for the overlapping pairs of images 0-1, 1-2, 2-3 ....9-0, delete unwanted control points on the sky and on the foreground.  You can drag a selection rectangle with the shift key held down and hit Delete to delete all the points in the rectangle.  Aim to end up with 5 or 6 points, say, on the very far distance.  Add points manually if needed, and there's also the Generate control points here function to generate a block of points within a selection box.( See Help=> Help for this screen while working in the Control Points tab).

Having got your control points assigned, select the Optimizer tab and click Advanced.  Set check boxes as in my completed project uploaded to https://www.sendspace.com/file/65ledq .  Click on Run Optimizer, and hope to get a good report.  Mine says Average distance 1.1 , with a maximum of 3.8.  If the figures are much worse than this, investigate any bad points (large control point distance) in the Control Points Table.  Just double clicking on a line there will take you to the point in the Control Points tab. Adjust or delete the point as required.

You can also try the Delete worst points option on the Control Points menu.  Repeat the optimization to if things have improved.

If the horizon is curved, use the straighten option on the Edit menu of the Panorama Editor.

I hope that gets you a little further.

John

[Paul Chubbuck]

John,

Yes, a little further, but stuck again. I successfully deleted all the sky control points, and some foreground ones, and added a few.

When I open your .pts file and go to Optomizer, I see only default settings, so it's unclear to me what I am supposed to change there.

Here's a screenshot of what I see with your file: https://drive.google.com/folderview?id=0BxmzkJ9EXQwsR1F6RnBxUlhtQ2c&usp=sharing

Thanks again,

Paul

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[John Houghton]

On Sunday, July 10, 2016 at 6:10:24 PM UTC+1, Paul Chubbuck wrote:

John,

Yes, a little further, but stuck again. I successfully deleted all the sky control points, and some foreground ones, and added a few.

When I open your .pts file and go to Optomizer, I see only default settings, so it's unclear to me what I am supposed to change there.

You are not supposed to change anything there in order to align the row of 10 images.  You would simply run the optimizer with those settings.

John

[Paul Chubbuck]

Ok, but when I Run Optimizer wiith those settings, I get an average control point distance of over 9 and when I "Create Panorama", I see significant stitching errors on the horizon.  See the same Google Drive link.

I don't know what I'm doing differently.  Here's my steps.

Load 10 horizon images.

Click "Wide Angle".

Change Focal Length to 20mm, which it is in the Phantom 4

Click "Align Images".

Click "Advanced" and Control Points

Delete all sky and closest foreground control points

Run Optimizer with default settings

Create Panorama

Again, I get significant discontinuities on the horizon, unlike your attempt.

Thanks again,

Paul

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[John Houghton]

On Sunday, July 10, 2016 at 7:30:11 PM UTC+1, Paul Chubbuck wrote:

Ok, but when I Run Optimizer wiith those settings, I get an average control point distance of over 9 and when I "Create Panorama", I see significant stitching errors on the horizon.  See the same Google Drive link.

I don't know what I'm doing differently.  Here's my steps.

Load 10 horizon images.

Click "Wide Angle".

Change Focal Length to 20mm, which it is in the Phantom 4

Click "Align Images".

Click "Advanced" and Control Points

Delete all sky and closest foreground control points

Run Optimizer with default settings

Create Panorama

Again, I get significant discontinuities on the horizon, unlike your attempt.

The reason is almost certainly the control points placement. Can you upload your project file so I can take a look.

John

[Paul Chubbuck]

It is there now, John.  Be aware that I am working with full res images whereas the ones I uploaded in the zip file were substantially reduced in size.

Thanks again.

Paul

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[Paul Chubbuck]

I just placed the full-size images (zipped) in the Google Drive folder, in case you need them.  I note that your average control point distance is 1.1, whereas mine is 9.5, so that's the problem alright, but how did you get such good control points?

Paul

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[John Houghton]

On Sunday, July 10, 2016 at 8:04:49 PM UTC+1, Paul Chubbuck wrote:

It is there now, John.  Be aware that I am working with full res images whereas the ones I uploaded in the zip file were substantially reduced in size.

Paul, The control points in your project are not restricted to the most distant features.  See this comparison between my points and yours: https://www.sendspace.com/file/waq3nh .  The parallax is so huge that you really do need to keep to the far distance.  You included image 0029, which is not part of the 3x10 set I used. It seems to be a rogue image. On the Optimizer tab, you should have y,p,r checked for all images except one (image 0 in this case). You have yaw for images 1 & 2 unchecked.  Oh, and it's best if you have points only between neighboring images e.g. 0-1, 1-2 but not 1-3.  Also, the last image in the row should link back to the first image.

John

[John Houghton]

On Sunday, July 10, 2016 at 9:12:11 PM UTC+1, Paul Chubbuck wrote:

I just placed the full-size images (zipped) in the Google Drive folder, in case you need them.  I note that your average control point distance is 1.1, whereas mine is 9.5, so that's the problem alright, but how did you get such good control points?

When the images are reasonably aligned, the Generate control points here option usually finds more points than the standard generator. So I drag out a letter box selection over the hills at the horizon to get points there and use the delete worst points to eliminate any not-so-good points.  I can do all of this more-or-less automatically fairly quickly, but it does take time and experience. 

John

[Paul Chubbuck]

Thanks, John.  I will try these latest suggestions.

Paul

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[Paul Chubbuck]

Ok, I took all those suggestions and got an excellent stitch on the horizon with just the 10 shots.

Now....how do I add in the remaining images without losing this?

Paul

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[Paul Chubbuck]

When I do the obvious, i.e. 

1. Save the pts file after optimizing the 10 horizon images.

2. Load the remaining images.

3. Align Images

The result is going back to square one with the lost of all those carefully selected control points.  How is this done?

Paul

On Saturday, July 9, 2016 at 6:03:24 PM UTC-6, Paul Chubbuck wrote:

[John Houghton]

On Monday, July 11, 2016 at 1:30:48 AM UTC+1, Paul Chubbuck wrote:

When I do the obvious, i.e. 

1. Save the pts file after optimizing the 10 horizon images.

2. Load the remaining images.

3. Align Images

The result is going back to square one with the lost of all those carefully selected control points.  How is this done?

Paul, I think it's more appropriate to continue this dialogue offline.

John