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Author Topic: 3D Model of Road Details from Close Range Photogrammetry | Forensic  (Read 2799 times)

Jaume

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Hi Everyone,

I was testing the PhotoScan in order to get a 3D model of crashed car and I need to admit that the results are good enough for further analysis.

But I am considering to apply close range photogrammetry to 3D reconstruction of road details (pavement, asphalt, ditches etc.). I know the UAV is the one of the solution but What about handheld non-metric camera?

Do you know some methodology (techniques) to prepare ground station for camera to get the best result after PhotoScan processing the data? How to pick station for camera? What about angles of camera axis? What if a road is sloping? The good practice is to taking photos along the parallel line to kerb using demanded overlapping or taking images in a circle (20-25°) from different ground stations?

I need to find some solution to 3D reconstruction of the road situation for forensics experts specialized in car accidents.

Thank you for taking part in this discussion.
« Last Edit: December 13, 2017, 11:06:57 AM by Jaume »

SAV

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Re: 3D Model of Road Details from Close Range Photogrammetry | Forensic
« Reply #1 on: December 15, 2017, 06:42:43 AM »
Hi Jaume,

You can find some useful tips about image acquisition plans on this website:
https://support.pix4d.com/hc/en-us/articles/202557459#gsc.tab=0

Regards,
SAV

Jaume

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Re: 3D Model of Road Details from Close Range Photogrammetry | Forensic
« Reply #2 on: December 19, 2017, 03:26:41 PM »
Thank you SAV for link to website with precious information.

This article considers the flight plan in order to get the best quality of the result using these described recommendations. I suppose the way to get better accuracy of the final road model is to take photos from 30-45 degrees aiming to center of the road and moving along the kerb line or road line. But what does it perform if we have a slope? Is some method gathering data to get the model depicts this slope using handheld camera?
« Last Edit: December 19, 2017, 03:58:17 PM by Jaume »

trolleway

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Re: 3D Model of Road Details from Close Range Photogrammetry | Forensic
« Reply #3 on: December 19, 2017, 06:26:12 PM »
I also trying to use Agisoft Photoscan to get road details for Openstreetmap improve - i want obtain coordinates of kerbs, poles and trees. Did not get satisfied results yet, but still many ideas. Here some ideas:
  • Wide angle lens (12 mm with crop-factor 2) will better than smartphone.
  • Fujifilm Real 3D camera with two lenses useless, due to small field of view
  • Video with 2-3 fps may be better than photos. Video can be easy exploded to frames in any operation system in terminal:
     ffmpeg -i ".MOV" -r 2 -f image2 -vcodec mjpeg -qscale 1 "frames/output_%05d.jpg"
  • Bridge camera with matrix optical stabilisation and fixed shutter value give better videoframes than smartphone

Now i waiting 7.5mm fisheye lens from Aliexpress.