For this project, near-vertical images that were taken of the grounds around the building were chosen for analysis. The intent was to use these images along with the D Joiner software to create a large single image that would show the lawn from a near-vertical point of view (POV). This could be useful for many purposes. Groundskeepers could use it to keep track of the vegetation on the property. In a germane example, this kind of large, aerial photo could be used by the planners and construction team that is building the new additions to the museum. Photos like this taken every few weeks could be a good overall progress indicator for the construction management.
D Joiner is software that can be used to stitch together panoramic images from multiple smaller images of a subject. It can be very useful for creating large views that a normal camera could never capture. For more information regarding the software, visit the D Joiner website.
Here are images one and two joined together.
Here are images two and three joined.
This third image is the result of the first two joined images being joined.
This is images four and five joined together.
This final image is an attempt to join the joined set that included images one, two, and three, as well as the join of images four and five into one large image.
As is shown by the images above, D Joiner can be used to join two or more images together to make a large whole, with minimal distortion. However, as the count of images increases, it becomes much more difficult to get usable output from the program. This is because of several limitations inherent to the program. The main problem is that D Joiner handles panorama images taken from one fixed position very well. The fact that the blimp was in motion and the point of view changes between the shots makes stitching them together challenging at times. As the point of view of the camera changes, the angle in which we see objects changes as well, and D Joiner has trouble at times getting these changes to display without massive distortion.
Another major issue with stitching together many images is the way D Joiner handles input and output images. All images inputted must have the same width and height in pixels. Which means that cropping and resizing the images is oftentimes necessary to make them even load into the program. This can be problematic, due to the way the program outputs images. When D Joiner has finished stitching together an image, the output is an irregular shape (not rectilinear) which is surrounded by a grey background (as seen in the final two images). If you try to join images that have this irregular shape and grey border, it does not work well, if at all. Cropping and resizing images to have the same resolution can remove so much information as to make it not worth the effort. The end result is that joining many images at the same time becomes troublesome, if not impossible.
Creating one large, high resolution image using the techniques described above is not feasible. So how could that goal be reached? The obvious answer would be to take the camera to a higher altitude, which would cover the ground in less shots and make stitching those shots together much easier. This would lower the resolution, but since D Joiner output has a lower resolution anyway, this would not be too much of a problem. Raising the camera higher has its own problems though. The aerial platform's effective height limit is 500 feet, because to fly any higher, a flight plan must be filed in advance. This is certainly feasible, but would take more time. Splitting the grounds of the museum into sections and joining several images to cover those sections, as has been demonstrated in this project, would be a workable and much less time consuming option.
Despite the failure of the D Joiner software to create a usable, large-scale mosaic of near-vertical images, the underlying aerial photography is still practical and usable. Joining many images and (to take it beyond the scope of this project) georeferencing them, could be a useful asset, but it is not a necessary one to enjoy the many benefits of small format aerial photography.
Aerial photos were taken during the class outing to Kansas City on Friday the 15th of April, 2005.
All other data collection and manipulation by Jeremy Aber.
© 2005 Jeremy Aber