Public Lab Research note

Using the Mapknitter 2 image placement using geotagged images

by patcoyle | March 23, 2015 05:03 | 1,886 views | 7 comments | #11714 | 1,886 views | 7 comments | #11714 23 Mar 05:03

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What I want to do

Try the new Mapknitter 2 feature to automatically place images that have gps coordinates in the EXIF information.

My attempt and results

I used images from Canon SX260HS, with integrated gps, in juice bottle rig with Delta 9' Levitation to make map of the pier at the Berkeley, CA marina and the parking lot in front of Skates restaurant (~1km walk).



Draft map (rough, not tweaked, first export in-progress) is at:


((Jeff Warren just implemented this, so now available.) I still haven't figured out how to imbed code to display the map in this note, like used to be able to in the prior version.)

The benefit of this feature is apparent for the images of the long pier. Without auto-placement, locating these images with little in the way of ground references is a problem. Auto-placement makes it easier. Particularly for images where a portion of the pier is near an edge of the image (rather than centered), just scaling and rotating the image, as placed, made alignment to the base map pier image pretty simple (when the key feature is centered, orientation is still potentially ambiguous after rotation).

Here is screenshot of demo map with two images auto-placed, with no further action.


Questions and next steps

The PL MK developers are pursuing additional ways to use the gps information for more than rough placement, and I'll try to follow their work.

Why I'm interested

Particularly in areas where the base map imagery lacks high resolution or the base map features are sparse such as: open water, prairies, jungle canopy or bush; gps placement is useful, perhaps essential, for mapping. In other areas it can be a convenient way to quickly place images in preliminary locations.



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Wow, so how much re-arranging did you have to do after uploading each image? Can you share a screen capture of what the images look like when they're auto-placed but not adjusted? I'm very curious how good they are.

We should be able to enable compass-heading arrangement soon as well; that may get even closer!

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Jeff, almost no translating of images. Along the pier, mostly just auto-place, scale and rotate. I just had message to re-export, so am trying again. Looking at map, you can see alignment isn't perfect, but I thought it was very impressive. I've got some other stuff today, but can try to post screen capture of what the images look like when they're auto-placed but not adjusted.

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Jeff, in body of note above, I added a screenshot of demo map with two images auto-placed, with no further action.

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Wow, that's great. Looks like sub-10-meter precision perhaps!

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@liz check this out -- see if maybe these will work in the new MK feature with auto-altitude and auto-compass!

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