Webodm: Bellus Example

[jonathanqv]

Hello i had a problem with the bellus example, first i ran it by default and it didn´t work, then i tried running with a high SFM number of processes, and i enabled the option "use-exif", but it return me a bad georreferencing Orthophoto; it was in the place but the image was smaller than te real map world. So my questions are:

• How does SFM number of processes work?
• What does "use-exif" option do? if i didn´t enabled the option, it doesn´t work?
• And what happened with the georreferencing?
• When you download bellus example, it has a ".gitignore" file, do i have to put this in folder "WebODM\app\migrations" ? or why does the example gives this file?

I am running WebODM in windows 10 with a docker container; my laptop has 8GB Ram; i ran the oracle virtual machine with 5 RAM and 2 processor.
Thanks a lot

[pierotofy]

• Higher sfm processes speed up the computation but use more memory.
• It ignores the ground control points file (if one is provided) and uses the geolocation information from EXIF tags (embedded in the images)
• I'm not sure; the Bellus dataset is quite old, I would recommend using a more recent dataset for performing tests and see if the error persists.
• .gitignore is an internal file for version control. You do not need to include it anywhere. Just upload the .JPG and the .txt (GCP) file.

Hope this helps.

[jonathanqv]

Yes, thanks a lot. I have two more questions.

• how can i know the ideal sfm processes number to input?
• And if i don´t enable the "use-exif" option, webODM work with "GCP" file and "EXIF" data? or wich one is better to use?

[dakotabenjamin]

ODM automatically detects a GCP file if it exists but if not it will default to EXIF. The use-exif tag is only really useful for if you have GCP but want to override and use EXIF for georeferencing.

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From: kirby031 [e-mail]
Sent: Thursday, August 17, 2017 2:13:33 PM
To: OpenDroneMap/WebODM
Cc: Subscribed
Subject: Re: [OpenDroneMap/WebODM] Bellus Example (#264)

Yes, thanks a lot. I have two more questions.

• how can i know the ideal sfm processes number to input?
• And if i don´t enable the "use-exif" option, webODM work with "GCP" file and "EXIF" data? or wich one is better to use?

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[jonathanqv]

Yes, i tried running it again with ubuntu but without checking "use-exif" and it gives me the same solution as when i ran it with windows. Why does it doesn´t get the correct georreferencing?

An Image:

Thanks a lot

[dakotabenjamin]

Try enabling skip-resize

[jonathanqv]

Thanks, i´ĺl try. What does "skip-resize" do?

[dakotabenjamin]

So I'm not in the office right now to confirm the issue but I believe that because the gcp was made for the full size image, when you resize the pixels won't line up.

[jonathanqv]

Thanks a lot dakotabenjamin, it worked and ran in half time. So when i ran the images by default it resizes? is The resize problem common?

[dakotabenjamin]

Only when working with GCPs. It's a bit of archaic code that now is not so relevant. I'm going to try to spend some time this week removing the whole process.

[jonathanqv]

are you trying to say that GCP alredy isn´t used?

[dakotabenjamin]

Sorry. I meant the Resize module.

[jonathanqv]

Oh, Thanks a lot for the support :)