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Author Topic: Align Chunks  (Read 3953 times)

scanlab.ca

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Align Chunks
« on: March 05, 2014, 11:02:05 PM »
Help me understand the Align Chunks feature better.

What does accuracy do and what does Point Limit do?

Say if I set:
Accuracy = Low
Point Limit = 200000

vs.

Accuracy = High
Point Limit = 40000

What sort of results should I be expecting from both of these scenarios?

Is Accuracy some sort of SIFT depth value, which dictates how many iterations the algorithm does at the alignment stage once points a set number of points has been reached?


Thanks!
Best regards,

Ruslan Vasylev | Scanlab Photogrammetry
S: https://scanlab.ca | E: ruslan@scanlab.ca | T: 1 (778) 991-5157

Alexey Pasumansky

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Re: Align Chunks
« Reply #1 on: March 05, 2014, 11:20:07 PM »
Hello Ruslan,

Accuracy and Point Limit has the same meaning like in Align Photos dialog.

Point based chunk alignment assumes matching images from different chunks.
Best regards,
Alexey Pasumansky,
Agisoft LLC

ngo

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Re: Align Chunks
« Reply #2 on: August 15, 2014, 12:38:56 PM »
Does increasing the Pointlimit in the Align Photo dialog only increas render times for aligning photos ?
Or does it also increase render times for my next step, generate dense cloud.

I?m wondering if it better to have a higher point limit for the "generate dense cloud"
Or if the alignment is fine with the standart settings it doesn?t give any better results.

Alexey Pasumansky

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Re: Align Chunks
« Reply #3 on: August 15, 2014, 12:45:05 PM »
Hello ngo,

The alignment procedure settings effect on the dense cloud generation stage indirectly. For example, if you've aligned the images with low accuracy and low point limit some images may not be treated as overlapping during dense cloud generation, even if they are. It will result in faster processing time, but may affect the result.
But using High accuracy and default point limit (or similar values) should not affect the processing time of dense cloud generation, unless the alignment results are incorrect.
Best regards,
Alexey Pasumansky,
Agisoft LLC

ngo

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Re: Align Chunks
« Reply #4 on: August 15, 2014, 03:05:42 PM »
Hey Alexey,
thank you for the quick reply.
I guess it?s a lot of try and error to get the right settings for time vs. quality.