Pre-sales query No. 2, Large area outdoor scans?

[Mr_Curious]

Hi,

One further question.

Would Agisoft be a good solution for the following?   I've been asked if I could scan a large outdoor area, specifically the scene of an accident at a roadway intersection.  I guess typically this sort of thing would be done using a lidar solution, but I am curious to know if Agisoft would also be a good candidate for such a job?  Has anyone used Agisoft for such a purpose?

Mr. Curious

[Wishgranter]

Have you some photos of scene that you describe ?

[Mr_Curious]

Have you some photos of scene that you describe ?

No I'm afraid that I don't access to any further details or data as this is for a pending legal case so the client has not provided me with many details.  The client has simply asked me if it would be "possible" for me to provide them with a scan of large outdoor scene.

I suppose this would be easy enough to test by simply taking some photos of a "similar" intersection.

What would be the best way to approach photographing this?  Should I just aim my lens at some central point in the center of the scene and then move along the perimeter of the roadway intersection while taking photographs?

Thanks!

Mr. Curious

[Wishgranter]

Try to cover "scene" with photos that overlap 60-80 % with photogrametry in mind, not the panorama photo style, that mean try to shoot so that you move around the scene. go shoot some photos and then will explain if is that good and what to do with photos that scene is better. and yes it can be done but as i wrote some guidelines must be folloved.... 

[Mr_Curious]

Try to cover "scene" with photos that overlap 60-80 % with photogrametry in mind, not the panorama photo style, that mean try to shoot so that you move around the scene. go shoot some photos and then will explain if is that good and what to do with photos that scene is better. and yes it can be done but as i wrote some guidelines must be folloved....

Hello Wishgranter,

Thank you for the explanation, I understand.  I will shoot some photos as soon as I can and post my results on-line for analysis.  The weather is very bad here at the moment, but I hope to do this soon.

Thank you again.

Mr. Curious

[Geo]

Hello Mr. Curious,

I have had good success with modeling outdoor scenes by using a compact camera or DSLR camera on top of a range pole or a telescoping hydro line pole - like the Tele-Pole.  You must be extremely careful of overhead power lines and MUST keep ten metres or more away.  The power can arc to your pole and electrocute you.  The Hydro poles are dialectic tested normally to 10,000 volts - don't try to test it - just do a hazard assesment before imaging at each scene.

You can easily build an adapter for the range pole to mount the camera.  I suggest that you take elevated panorama images from various locations as well as the modeling images.  You can set your camera to take HD video images and just walk around the site in a systematic manner to cover the scene.  Photos can be extracted at a one second rate or so with DVD Videosoft (free) very easiy and then used to create the model in Agisoft Photoscan.  You may also want to try fabricating a manual shutter trigger that will hold the shutter down in continuous shoot mode.  The camera should be pointed downwards at an angle not more than 30 degrees to the nadir for best results.

The scene models should work well fom that type of source image.  You will likely have trouble obtaining clean models of shiny obects such as cars.  This is where the panorama's can fill the visual gap of any objects that do not model well.

I hope that helps.

Jim

[Mr_Curious]

Thank you Jim for the GREAT suggestions and advice!!  You've got me thinking now :-)  Looking forward to trying this as soon as it stops snowing :-/

Thanks again.

Mr. Curious

Hello Mr. Curious,

I have had good success with modeling outdoor scenes by using a compact camera or DSLR camera on top of a range pole or a telescoping hydro line pole - like the Tele-Pole.  You must be extremely careful of overhead power lines and MUST keep ten metres or more away.  The power can arc to your pole and electrocute you.  The Hydro poles are dialectic tested normally to 10,000 volts - don't try to test it - just do a hazard assesment before imaging at each scene.

You can easily build an adapter for the range pole to mount the camera.  I suggest that you take elevated panorama images from various locations as well as the modeling images.  You can set your camera to take HD video images and just walk around the site in a systematic manner to cover the scene.  Photos can be extracted at a one second rate or so with DVD Videosoft (free) very easiy and then used to create the model in Agisoft Photoscan.  You may also want to try fabricating a manual shutter trigger that will hold the shutter down in continuous shoot mode.  The camera should be pointed downwards at an angle not more than 30 degrees to the nadir for best results.

The scene models should work well fom that type of source image.  You will likely have trouble obtaining clean models of shiny obects such as cars.  This is where the panorama's can fill the visual gap of any objects that do not model well.

I hope that helps.

Jim