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Author Topic: Smooth contours...  (Read 4396 times)

Yoann Courtois

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Smooth contours...
« on: August 28, 2017, 06:41:24 PM »
Hello !

I would like to get smooth contours (+- 5cm) on a model which has high resolution data (Area = 17.5ha with GSD = 1.6cm)...
There is indeed no tools to smooth those contours on a hand, and no possibility to get low resolution DEM on the other one...

Any help would be appreciate again !

Regards
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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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SAV

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Re: Smooth contours...
« Reply #1 on: August 29, 2017, 08:46:43 AM »
Hi Yoann,

Use QGIS (or ArcGIS) to generate and smooth contour lines ... and add SMOOTH CONTOURS to the feature request section of this forum.

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SAV

Yoann Courtois

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Re: Smooth contours...
« Reply #2 on: August 29, 2017, 09:29:16 AM »
Hi SAV !

Thanks for this advice !
I wasn't sure it was already possible to do that in PhotoScan so I posted here in General section.
I'm going to move it to Feature request section.

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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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SAV

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Re: Smooth contours...
« Reply #3 on: August 29, 2017, 12:01:25 PM »
Hi Yoann,

As far as I know there is only a 'simplify contours' option in PhotoScan (see attached image). But 1) I am not sure what it really does and 2) you cannot choose the level of 'simplification/smoothing'.

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SAV

Yoann Courtois

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Re: Smooth contours...
« Reply #4 on: August 29, 2017, 12:18:20 PM »
Hi SAV !

Guess you still work on 1.2 version of PhotoScan because your screenshot come from its panel.
In 1.3, "Simply contours" became "Prevent intersections".
No idea what's the aim of one or the other but still..

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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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SAV

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Re: Smooth contours...
« Reply #5 on: August 29, 2017, 01:17:05 PM »
Yep, version 1.2.6. Too many Python scripts that I don't want to adapt/change so they run in 1.3.

Prevent intersections? Interesting. Contour lines, by definition, cannot intersect because that would mean there are two different elevation values for the same pixel/point.
Not sure how PS extracts contour lines, but theoretically there should be no need for the 'prevent intersection' option.

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SAV

Yoann Courtois

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Re: Smooth contours...
« Reply #6 on: August 29, 2017, 01:30:14 PM »
Ahah of course... I understand you...
Since, you really miss a lot of improvements of 1.3 !
Just regarding the basic calculations which are really faster and give us better results !
With 1.3 we indeed had a completely new API vocabulary. But I don't thing it gonna change again in 1.4.
Maybe you should wait a while and update your scripts with next 1.4 !

Yes you right, I though the same the moment I saw it.
I don't know either how contours are extracted, but it should have a bit of smoothing already. And if you ask for really small gap between contours (one each cm), the smoothing on random altitude area may give you intersected contours.

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Yoann COURTOIS
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Lyon, FRANCE
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SAV

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Re: Smooth contours...
« Reply #7 on: August 29, 2017, 05:02:52 PM »
I have read in the change log file that PS is now using CPU + GPU for image alignment (instead of CPU alone), which should speed up the whole process. Do you have an estimate of how much?

What do you mean with better results? Have they also improved some other parts of the code?

Yes, version 1.4 should be coming out soon. I'll probably 'bit the bullet' then and upgrade PS and my scripts ;-)

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SAV

Yoann Courtois

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Re: Smooth contours...
« Reply #8 on: August 29, 2017, 05:55:14 PM »
I never tried the test because I would need to put 1.2 back on my computer.

I would also say it depend on your set up.
On my computer as an exemple the depth maps calculation (for dense cloud) is made at 5% by CPU and 95% by the GPU.
For the alignment, detecting and matching points are calculated on both CPU and GPU, whereas the camera location estimation is calculated on CPU only.  The time-saving is huge !

For other better result, I would say the ground extraction tool, which had several problem in 1.2, is working perfectly on 1.3 (I have extracted ground from flowers by using 5 cm max distance...)

Many new tools are pretty useful, such has shapes on pictures, or ruler which can measure point coordinates directly on pictures, model or orthomosaic...
You really miss something ;)

Regards
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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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SAV

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Re: Smooth contours...
« Reply #9 on: August 30, 2017, 08:02:56 AM »
Thanks for sharing your experience.

I have never really had good/consistent results using the ground extraction tool. Good to know that this has changed since version 1.3

Time savings in processing are always welcome ;-) I might upgrade sooner than I initially anticipated.

Regards
SAV

I never tried the test because I would need to put 1.2 back on my computer.

I would also say it depend on your set up.
On my computer as an exemple the depth maps calculation (for dense cloud) is made at 5% by CPU and 95% by the GPU.
For the alignment, detecting and matching points are calculated on both CPU and GPU, whereas the camera location estimation is calculated on CPU only.  The time-saving is huge !

For other better result, I would say the ground extraction tool, which had several problem in 1.2, is working perfectly on 1.3 (I have extracted ground from flowers by using 5 cm max distance...)

Many new tools are pretty useful, such has shapes on pictures, or ruler which can measure point coordinates directly on pictures, model or orthomosaic...
You really miss something ;)

Regards