Can I create photogrammetry mesh from the photos taken by mobile phones / tablet in Site Scan / SURE for ArcGIS?grammetry mesh?

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JackFanZhang
New Contributor II

Hello, 

I would like to have our field crews be able to take photos of the work site, and upload to the cloud to automatically generate mesh out of it. Is the workflow possible currently with any exiting ESRI solutions? thanks.

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Brooks_SummitGeo
Regular Contributor

Yes you absolutely can, in any photogrammetry software. You just need to ensure you have sufficient overlap between images, and have geotagging enabled. Also, the principle of standard photogrammetry is that the parallax of the subject matter changes between images, so the photographer needs to travel (walk) whilst taking photographs, not just stand in one location and take lots of panoramas. (Note: Photogrammetry from 360 panoramas is possible but not recommended or at all accurate without specialist equipment)

I will caveat this comment after rereading your question, as you mention having your team walk around a "work site" taking pictures. There are many reasons why drone based photogrammetry has become the defacto solution for this type of work:

1: terrestrial photogrammetry is better suited to individual subject matter (objects) or building facades. An overview of a work site captured by mobile phone would be very difficult to achieve (and repeat successfully time and time again) due to the need for sufficient overlap and coverage of the subject matter.

2. Health and safety. Do you really want someone walking around a work site taking 1000s of photos.

3. Photogrammetry works best with homogenous imagery. (Fixed iso, white balance, aperture) and walking around will create far greatly exposure and light variability.

You could look into achieving this with a 360 fisheye camera like a Ricoh Theta and capture 360s around the site, but I'm unsure if sitescan or d2m will support these sort of workflows.


David
..Maps with no limits..

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Brooks_SummitGeo
Regular Contributor

Yes you absolutely can, in any photogrammetry software. You just need to ensure you have sufficient overlap between images, and have geotagging enabled. Also, the principle of standard photogrammetry is that the parallax of the subject matter changes between images, so the photographer needs to travel (walk) whilst taking photographs, not just stand in one location and take lots of panoramas. (Note: Photogrammetry from 360 panoramas is possible but not recommended or at all accurate without specialist equipment)

I will caveat this comment after rereading your question, as you mention having your team walk around a "work site" taking pictures. There are many reasons why drone based photogrammetry has become the defacto solution for this type of work:

1: terrestrial photogrammetry is better suited to individual subject matter (objects) or building facades. An overview of a work site captured by mobile phone would be very difficult to achieve (and repeat successfully time and time again) due to the need for sufficient overlap and coverage of the subject matter.

2. Health and safety. Do you really want someone walking around a work site taking 1000s of photos.

3. Photogrammetry works best with homogenous imagery. (Fixed iso, white balance, aperture) and walking around will create far greatly exposure and light variability.

You could look into achieving this with a 360 fisheye camera like a Ricoh Theta and capture 360s around the site, but I'm unsure if sitescan or d2m will support these sort of workflows.


David
..Maps with no limits..

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NicoBonnafoux
Esri Contributor

Hi @JackFanZhang

@Brooks_SummitGeo's answer was very complete, thanks for that. 

Esri photogrammetry software is optimized for aerial imagery (Site Scan and Drone2Map being focused on drone imagery, SURE for ArcGIS on piloted aircraft imagery, and Ortho Mapping covering the aforementioned as well as satellite and historical scanned imagery). 

While we dont test Site Scan or Drone2Map processing with images captured from the ground, as long as the images are georeferenced and captured with proper overlap and sidelap, they should process fine in either software. Capturing this imagery manually can be challenging and time consuming though, which is why most of users use drones and automated captures using an app like Site Scan Flight. Some users will do the bulk of their imagery capture with a drone, and then complement the image set with a few images captured from the ground. 

Regards,
Nico

JackFanZhang
New Contributor II

Thanks a lot David and Nico for the suggestions and comments. Definitely understanding the safety risk might be exposed when the crews need to walk around a site to take the photos when doing ground survey.


I realised I should describe more clearly about the work site in my original question. The objects we want to take photo mesh are the ground trenches less than 2m x 5m in urban areas, often less than 1mx3m. These trenches are exposed and backfilled one by one during the inspection. Using drone might be a bit overkill for it in my view.


Yes photogrammetry should work regardless whether the photos are from air or ground, that's I try to find out if the SiteScan solution could be used in similar way as Pix4DCatch or ContexCatpure in terms of mobile reality capture from smartphone/tablet, as an addon to our traditional GIS field data capture (point/line/polygon + photos) .

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Brooks_SummitGeo
Regular Contributor

@JackFanZhang funnily enough I used a plane and drone for just this type of work. But it was for 300x 5mx30m archaeological trenches over a 10sqkm area of proposed road diversion. The aerial survey is excellent for capturing a "before" snapshot of the site, and you can then undertake more targeted "after" surveys, in order to capture the delta on the ground as soon as works are complete.

If you are basically walking around a trench and angling the camera slightly downwards, then you may get success going your route, but there are limitations and "embuggerances" such as ensuring you crop the sky portion of your images, and ensuring good manual overlap and light conditions.

If you are more interested in predictable performance and success, you'd be far better off with a drone. Even just a sub-250g DJI Mini 2 using Quick Shot Circle mode (point-of-interest orbit) would take about 2 minutes from start to finish.


David
..Maps with no limits..
JackFanZhang
New Contributor II

Yes David. I thought about DJI Mini 2 as well, though it might requires a bit set up but it solve the challenges from walking with a handheld camera as you mentioned.  However,  I couldn't see if Mini2 is supported by Site Scan Flight or Site Scan for ArcGIS LE according to Site Scan Flight for ArcGIS – Matrix of Supported ... - Esri Community Without using Site Scan Flight, not sure how I set the drone to take photos with the minimal required overlap...

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