Stitching Streetview

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Now that streetview rigs become affordable for amateur usage it is time to cover the stitching process.
This page is thought as a starting point. Please add your findings.

Contents

Whats the difference to a panorama rig?

Streetview rigs

  • have more than one camera.
  • take all images at once, not one image after another.
  • always have a parallax error.
  • are most likely for automated mass-production of panoramas.

What does a streetview rig look like?

Amateur streetview rigs:

By Jan Martin:
First model from a 360 degree security camera:
http://www.diy-streetview.org/forum/viewtopic.php?f=2&t=11
Second model from 2x Canon A570 IS cameras and 2x Nikon FC-E8 fisheye conversion lens:
http://www.diy-streetview.org/2010/07/28/new-streetview-rig/

By Matt McClelland:
The 4x GoPro HD backpack streetview rig :
http://www.diy-streetview.org/2010/10/19/gopro-hd-digital-cameras-for-streetviews/

Unavoidable parallax error

In theory the best result one can expect from a multi-camera rig (aka streetview rig) is a stitching error that is the size of the largest distance of the lenses of the rig. So if the streetview rig has two lenses whose NPP (no parallax (error) points) are 7 cm away, 7cm also is the smallest stitching error on can hope for. Therefore it is desirable to place the lenses as close as possible together. To reduce stitching errors it also is desirable to have the light falling through all the lenses meet in one (virtual) point in the middle of the rig. And have all the lenses in the same distance from this point.

How to determine the lens parameters for a hugin template for a streetview rig?

To create a template.pto file for a streetview camera one needs to provide the lens parameters a, b, c and v for each lens to the template.

To determine a, b, c and v values you need to take images for a whole 360 degree panorama with each lens. Depending on the number of cameras your streetview rig has, you need to turn it differently. What's needed is a 50% overlap of the images.

So for a streetview rig with 4 lenses around like Matt's you need 8 images taken at 45 degrees apart. Take the images at 3 different motives, just in case.

Ideal motive is in a well lit church or in a shopping center with lots of details on the walls and ceiling. Place your rig on a tripod and with the same distance to all the walls. Level your tripod. Right into the middle of a large open space with nothing nearby. When doing this outdoors go for tall buildings all around, at the same distance. Make sure there is a building right at the seam of the images. Just in case you might want to take two series started 22 degrees apart.

Then follow this article for the stitching:
Original article: http://www.diy-streetview.org/how-to-lens-parameters

How to make a hugin template for stitching streetviews?

See http://www.diy-streetview.org/2010/02/27/streetviews-by-hugin

How to do mass-stitching?

See http://www.diy-streetview.org/how-to-stitch-all-files-in-a-folder


Copyright notice by Jan Martin:
I hereby grant the right to use texts from my website http://www.diy-streetview.org in this wiki.

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