Smathermather's Weblog

Remote Sensing, GIS, Ecology, and Oddball Techniques

OpenAerialMap, OpenImageryNetwork, MapKnitter, OpenTerrain, and OpenDroneMap (cont. 1)

Posted by smathermather on June 7, 2015

Citing my previous post, let’s move on to more specifics on my thoughts regarding the integration of OpenAerialMap, OpenDroneMap, and MapKnitter as projects.

Image from kite over Seneca Golf Course

OpenDroneMap <3 OpenAerialMap.

OpenAerialMap will become a platform by which drone users can share their imagery under an open license.

So, as the metadata spec for OpenAerialMap and OpenImageryNetwork matures, and as soon as a publicly available place for drone users to push their data comes online, ODM will write appropriate metadata and geotiffs to go into OIN to be indexed by OAM. Probably as an added bonus, ODM should be able to optionally auto-upload outputs from to the appropriate node on the OpenImageryNetwork.

Lincoln Peak Vinyard

OpenDroneMap <3 MapKnitter.

MapKnitter / ODM integration is pretty straight forward in my mind too. There are ways that MapKnitter complements ODM, and vice versa. ODM does not have a graphical user interface at this time. MapKnitter promises to fill that role in a future OpenDroneMap implementation. MapKnitter has no image blending or auto-matching tools. OpenDroneMap will soon have both.

  • Ways MapKnitter may help OpenDroneMap:
    • MapKnitter’s clever use of Leaflet to handle affine transformation of images is really exciting, and may help with improving final georeferencing for ODM datasets.
    • Regarding the above, one really useful thing for fliers launching balloons, drones, and kites without GPS would be the ability to quickly and easily perform really approximate georeferencing. I would envision a workflow where a user moves an image to its approximate position and size relative to a background aerial. ODM would be able to take advantage of this approximate georeferencing to optimize matching.
  • Ways OpenDroneMap could benefit MapKnitter
    • For large image datasets, matching images can be very tedious. Automatic feature extraction and matching can help. OpenDroneMap could be adapted to serve back match information to Mapknitter to ease this process. This will become increasingly important as MapKnitter raises the ~60 image limit on images that it can process.
    • A near future version of ODM will have image blending / smoothing / radiometric matching. For the server portion of the MapKnitter infrastructure, this feature could be a really useful addition for production of final mosaics.

These projects (plus OpenTerrain…) are really exciting in their own right. Together, they represent amazing opportunities to foster, cultivate, process, and serve a large community of imagery providers, from individuals and small entities capturing specific datasets using kites, drones, and balloons, to satellite imagery providers hosting their own “image buckets” of open imagery data. Exciting times.

Image over Groth Memorial from kite

Posted in 3D, Bundler, Camera Calibration, FOSS4G, Image Processing, OpenDroneMap, Optics, Photogrammetry, PMVS | Tagged: , , , , , , , , , , | Leave a Comment »

OpenAerialMap, OpenImageryNetwork, MapKnitter, OpenTerrain, and OpenDroneMap

Posted by smathermather on May 29, 2015

This tweet:

is the beginning of some fruitful discussion, I suspect. There are some really awesome projects gaining momentum. I’ll give an overview of them as best I am able.

Kite aerial photography image over bridle riding ring.

Kite aerial photography image over bridle riding ring.

Let’s start with the one nearest and dearest to my heart (if you’ve been reading my blog, you can skip this part): OpenDroneMap. OpenDroneMap is an open source toolkit for processing drone, balloon, kite imagery into geographic data. It does this by using fully automated feature-matching between images, which create a 3D point cloud. From that, we can create a 3D surface (mesh), textured mesh, and orthophoto. This guy says it better:

But, it’s just a stand alone, Linux (Ubuntu)-based tool. It requires some geekiness to run, and it does not (at least not yet) act as a platform.  By that I mean, generically, you can’t just upload images to it and get the wonderful output from a service, and we don’t have a place to store and share all this wonderful data that comes from and will be coming from drones and other aerial platforms. This is where (from my selfish perspective) the other projects are so well timed… .

Screenshot of DevelopmentSeed's introductory post for OpenAerialMap

Let’s start with OpenAerialMap. From the Development Seed blog post on it (yes, you should follow the link. Don’t worry, I’ll wait until you return):

OpenAerialMap is a set of tools for searching, sharing, and using open satellite and drone imagery. This initial release includes the core infrastructure to catalog petabytes of open imagery. It also includes an extremely usable API and an elegant web interface to submit, search and download available imagery.

This is a reboot of a couple of previous attempts at solving this problem space, and it’s really exciting to watch passionate and brilliant work take place to make this happen. Also, this is not an easy problem space, and is being really thoughtfully simplified and implemented.

(As a side note, I’m not going to get into the distinction between OpenAerialMap and OpenImageryNetwork — not today anyway)

Preview of Open Terrain tumblr page

Preview of Open Terrain tumblr page


Open Terrain is a project for which a portion of its scope is to do for terrain models what OpenAerialMap and OpenImageryNetwork will do for open aerial datasets. The projects are informing each other and growing together, which is awesome collaboration to observe.

Finally, Mapknitter has recently been rebooted too, and it’s now a really elegant tool for taking a few aerial images and knitting them into a usable map (ok, it always was p. cool — now it’s even more elegant). What’s great about MapKnitter is it specifically addresses the problem of georeferencing balloon, kite, or drone images in a simple-to-use interface in the browser.

Snapshot of MapKnitter landing page

So, back to the question:

Bravo, yes. Lets. I have been thinking about, talking to people, discerning the strengths, overlaps, and complementary fittings of these projects as they have emerged. We are headed toward some really great things… . More specific thoughts to come.

Posted in 3D, Bundler, Camera Calibration, FOSS4G, Image Processing, OpenDroneMap, Optics, Photogrammetry, PMVS | Tagged: , , , , , , , , , , | 1 Comment »

BASH script for adding directional / compass arrows to image

Posted by smathermather on April 29, 2015

I got a request today to extract the compass bearing from a set of photos, and add a rotated north arrow to those images in visual form so end users can see if the picture was while the camera was pointed north, or east, or NNW, etc.. Below is a photo pointing mostly East.

With BASH and a little Imagemagick, this was a pretty easy build. First we extract the direction info, and transform it to Cartesian coordinates so our rotation numbers will be correct. Then we rotate our arrow, maintaining transparency of background. Finally we use the “composite” command to overlay our rotated arrow with the original image.


(code edited to remove transformation to cartesian — rotation in imagemagick is polar…)


for image in `ls *.JPG`
	# trim off leading and trailing spaces in image variable
	image=`echo $image | xargs`
	# get non-extension portion of name
	name=`echo $image | awk -F'.' '{print $1}'`
	# extract angle from EXIF, and turn into variable
	angle=`exif $image | grep 'Image Direction' | awk 'BEGIN { FS = "|" } ; { print $2 }' | sed 's/M//g' | xargs`

	# create rotated and scaled arrow for image
	convert -rotate $angle -transparent white -resize 300x300 arrow-hi.png arrow-hi_$angle.png
	# overlay that arrow on original image
	composite arrow-hi_$angle.png $image $name.png
	# perform a wee bit of cleanup

	rm arrow-hi_$angle.png

addendum — almost forgot the repo:

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Moar kite flight pics

Posted by smathermather on April 27, 2015


Posted in 3D, Bundler, Image Processing, OpenDroneMap, OpenDroneMap, Optics, Photogrammetry, PMVS, UAS | Tagged: , , , , , , , , , | Leave a Comment »

Kite flight (too windy for balloons, ahem “aerostats”)

Posted by smathermather on April 20, 2015

Inflation of aerostat

The aerostat hanger.

The end of the string.

The 9-footer is just so stable. But not enough wind to lift the cameras this day.

And so we send up the 16-foot workhorse. See that little dot? That’s the camera array.

The 16-footer flew nice and vertical, but pulled really hard. Processed images to follow soon.

Canon S100s from Kaptery — the silver one is an NIR adapted one; the black one is RGB color.

Edit: forgot the camera array:

CIR image from balloon:

IR image from the flight.

IR image from the flight.

Posted in 3D, Bundler, Image Processing, OpenDroneMap, OpenDroneMap, Photogrammetry, PMVS, UAS | Tagged: , , , , , , , , , | Leave a Comment »

FOSS4gNA Photos, well, ok, just San Francisco

Posted by smathermather on March 13, 2015

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North Carolina GIS Conference

Posted by smathermather on March 7, 2015


NCGIS was an excellent conference, and this year was my first attending / presenting. Bravo to the organizers, who themed it Mobile and Global, but confessed that Mobile, Global, Open would have been more apropos.

To catch screen captures and audio for the presentations, see this temporary location:

which is organized by room numbers, so check out the schedule: .

My favorite new ideas from the conference, aside from talks by Randale Hale, Howard Butler, and Paul Ramsey were local to NC State University, with Helena Mitasova from the Open Source Geospatial Research and Education Laboratory.

See especially their Tangible Landscape which ties a sandbox in to real-time GRASS DEM processing (flow accumulation, viewsheds, fire modeling, etc.):

Screen capture of tangible landscape video.

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OpenDroneMap Video for FOSS4GNA

Posted by smathermather on March 6, 2015

Thanks to some brilliant work by our Interpretive Technology Technician, we now have a little video for FOSS4GNA on OpenDroneMap. Come see my presentation next week in San Francisco, Weds. at 13:30 (1:30PM):


Posted in 3D, Bundler, Camera Calibration, FOSS4G, Image Processing, OpenDroneMap, Optics, Photogrammetry, PMVS | Tagged: , , , , , , , | 6 Comments »

OpenDroneMap — GCP file format

Posted by smathermather on March 1, 2015


So much documentation to catch up on for OpenDroneMap. Probably the most important missing element is documenting the ground control point file format. This will be a file name gcp_list.txt to be placed in the root of the image directory that you are processing.


The ground control point file associates locations in the input raw images with geographic positions, allowing for the output of an orthophoto and georeferenced mesh. It can augment or replace the need for geographic coordinates in the exif headers of the input images.


I mention this file briefly in a previous post, but let’s get into the weeds a bit on how to create one. The format is a simple text file. The header, or first line, is a descriptor of the coordinate system. This is not a formal thing, so don’t worry about format for this line.

The subsequent lines contain the x, y, and z of the ground control location in your local coordinate system, the pixel and line number of the location in the image, and the imagename itself. A minimum of 3 GCPs is necessary:

x y z pixelx pixely imagename

So, for example, if I mock up a version for the Langley dataset, I get something like this:

544256.7 5320919.9 5 3044 2622 IMG_0525.jpg
544157.7 5320899.2 5 4193 1552 IMG_0585.jpg
544033.4 5320876.0 5 1606 2763 IMG_0690.jpg

Note that my elevations are all the same. I was lazy, and assumed that there’s minimal topography and Langley, and that we are 5 meters above sea level. It is far better to put real values here, derived from an elevation dataset.

More on the how:

So, how to get these numbers? I loaded my raw unprocessed jpegs into QGIS. As I mouse over the image, it gives me coordinates, like “3044 -2622″. These are pixel values. I ignore the sign on the Y value.

For the X and Y values, I just used a Leaflet slippy map with a lat/lon pop-up: It would be better if I had GPS values from the field (preferably map grade) or survey values, but this quick and dirty adaptation of will at least get my map in the correct part of the world. I plugged the lat/lon values I get into Montana State’s UTM converter, though this is a slow method if I am doing a lot of points.

Screenshot of coordinate collection process

Screenshot of coordinate collection process

Screenshot of coordinate collection process -- a total of 3 points have now been collected.

Screenshot of coordinate collection process — a total of 3 points have now been collected.

Finally, I save my text file as gcp_list.txt, save it in the directory that contains my raw images, and run the script, and sit back and get some coffee. Output will be a subdirectory with a name similar to reconstruction-with-image-size-2400-results.

And now I’ve added this to the wiki:

Posted in 3D, Bundler, Camera Calibration, FOSS4G, Image Processing, OpenDroneMap, Optics, Photogrammetry, PMVS | Tagged: , , , , , , , | Leave a Comment »

OpenDroneMap — Now with animated GIFs

Posted by smathermather on February 20, 2015

Ok. I confess, clickbait. OpenDroneMap won’t make the animated gifs for you. But come on! it can make the 3D models which you can view in Meshlab or where ever, and then create animated gifs. Ok ok. I promised animated gifs. These are from data contributed to our test dataset repo by  Aaron Racicot and Tomasz Nycz respectively.

View of 3D textured surface model of Langley, BC

View of 3D textured surface model of Langley, BC

3D of kite aerial photography dataset

3D view of farm from Kite Aerial Photography (revised description)


Posted in 3D, Bundler, Camera Calibration, FOSS4G, Image Processing, OpenDroneMap, Optics, Photogrammetry, PMVS | Tagged: , , , , , , , | 7 Comments »


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