Photo Rectification for Engineering design

Discussion in 'Digital Darkroom' started by gary_hamilton|3, May 22, 2009.

  1. Hello:
    I am a Professional Land Surveyor & amateur photographer. We do highly detailed ground surveys and aerial surveys for many design projects.
    I have a client that needs a basic plan prepared to show some repair work to a Rip Rap (stone slope) at a reservoir.
    He needs to be able to mark up a photo that is to scale to tell a contractor where to make repairs and the approximate square footage of each repair.
    Sounds like a perfect application for terrestrial photogrammetry. We are only looking for low precision +/- 2' of true scale for four faces of the retention basin. It's small, 400 x 400 with good access and visibility.
    I am thinking of photos at each face taken square on to minimise distortion. I will mark each face with reference marks & get measurements between the ref marks with my survey instrument.
    I am looking for a software package that will allow "rubber sheeting" or Rectification of each face to turn the photos into flat faced scaled images.
    I know there are software packages out there that Architects use to do building face surveys. This is a very similar application.
    I would like a suggestion for a reasonably priced software that is fairly powerful to allow us to accomplish this task.
    P.S. final product tiff, jpeg, DXF to load into AutoCadd.
  2. 400 by 400 feet? Yards? Meters? Either way, an inexpensive way to do this would be with Google Sketchup Pro.
    Look here and see if this would work for you. Other than that, probably just Photoshop.
  3. Gary; One has Autocad map for 5.5 grand. One can download a free trial version.
    On can also just farm out the job; ie the software part too; sort of link renting several clusters of prisms to shoot an ultra long baseline shot
    Are you planning in getting into aerial/GIS/photo/mapping work or just looking for a 200 buck rubber sheet program?
    Have you posted this question on the POB message board?
  4. Gary: Of course, Photoshop will do basic perspective correction. Keep in mind, though, that the result will not be the same as taking a shot perpendicular to the slope face if the face is not flat (e.g. some stones sticking out or holes in the slope). Even if your correct for perspective you can't change the fact that the camera is looking at the face from an angle and thus imaging topography from an angle. In this case you best option is taking the picture from a cherry picker, a helicopter, or with the camera attached to a weather balloon or a kite.

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