Photogrammetry is the beautiful fusion of mathematics, photography and computer graphics.
Through the process of shooting and analyzing multiple photographs of a given subject an extremely accurate textured 3D model of the original subject can be created using special software.
– LEARN THE BASICS –
HOW TO SHOOT
Golden Rule: Never use flash
When shooting an isolated object, move around the subject in a circle pattern at 20 degree intervals so that you get about 36 images for one full rotation around the entire object. Keep the same distance from the object, and keep it centered in the screen. If the subject is not something you can move around, such as the canyon wall of a petroglyph, it is important to get an overlap of 50 percent or more in your images and make sure not take all images from one position. (for example, it would be best to keep walking along a canyon the wall as you photograph the petroglyph, rather than pivoting your camera from one position as if it were mounted on a tripod. Take a step to the left or right between each photo, as parallax is necessary for photogrammetry to work. Ideally: shoot high, medium and low angles of your subject for best results. Keep your camera in landscape view when shooting unless you have turned off auto rotation in your menu settings.
A camera that shoots sharp images is the best choice. A DSLR camera with 12 megapixels or better is preferred. (Such as consumer models made by Canon, Nikon, Sony, etc.) Smartphone cameras with correct exposure and no motion blur, are acceptable as well, though the higher resolution the camera the better quality of the photogrammetry solve.
USING A LENS
Try to use a Prime lens with a DSLR like a 24mm or 50mm lens with your camera. If using a zoom lens, you must be sure to lock the lens at single setting for the entire series of photos. (In that case we would recommend using gaffers tape over the barrel of the lens, to prevent it from shifting.)
Shooting images with correct exposure is important. (Try not to clip your darks or your highlights.) Make sure your images are sharp, not blurry. (Tripods or other bracing to make sure the camera is not moving are ideal, but a steady hand is good enough.) Try to achieve even lighting whenever possible, such as when the sky is overcast.
When shooting with a DSLR, keep your ISO setting as low as possible to avoid a noisy image. Ideal ISO settings are in the range of 250 to 320 (that is, the native ISO of your particular camera) but usable ISO settings on recent models by Canon for example can be as high as 1000 if need be. Try to shoot in manual mode so that all your images of a given subject have the same exposure. RAW image files are best, however JPG images with no compression can also work.
Keep your f-stop settings around f/8 to f/16 for best results (this will generate a larger depth of field.) Having everything in focus in your photos is ideal.
Avoid shooting surfaces that are mirror-like or completely transparent whenever possible. Also, large areas in an image with no detail such as a white wall are not good. Ideal surfaces are matte with lots of high frequency detail, such as the rock of sculptures, the bark of trees and the bumpiness of stucco walls etc.
Avoid shooting moving objects.
READY TO DONATE PHOTOS?
With your photos we will build a digital Ark. We use a cloud-based file transfer service provided by WeTransfer. Donating photos is easy.
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