Only achieving a good texture is a more difficult step in post-processing. The iPhone has a good camera that can be used for high-resolution photogrammetry scan with sub-millimeter resolution. If you are using a DSLR or a mirrorless camera, you should already know how to achieve this. Also, the depth of field needs to be as big as possible. We need to remember that the images need to be as sharp as possible. And this is done to ensure that we have not forgotten anything. These can be random shots of the most complex surfaces, or the surfaces with fine detail like face, eyes, ears, palms etc. When you know that you have all the necessary images, like the top of the sculpture’s head, the back side, the surfaces that look down etc., it is time for the final “kill” shots. The shooting needs to be straight or from only a slight angle in relation to the surface. You should always follow the shape and curves of the object. And the images with different ISO need to the pre-processed separately. Images with different ISO settings tend to have different “noise pattern” or noise level. You should avoid changing the ISO settings on your camera during this process. If you are shooting like this, you can adjust camera settings so that any backlit side of the object is not underexposed and a light side is not overexposed. After that, take a small sidestep and repeat vertical movements but from the top to the bottom. Shoot from below, move the camera up shoot again and so on. In some lighting conditions, for example, an object in a cave and one side darker than other, better use other technique. Shot, small side step, shoot, small side step, shoot… after finishing the loop, raise the camera and start with the next loop and so on. When you have a basic plan for movement around the object and already know the part of the object that needs additional attention, you can start shooting. Or the software just does not align these images correctly. Such images do not have parallax changes, and as result, no depth information that required for calculation of the mesh details. Photogrammetry software sees them a single panoramic image. I have seen many scans made by hobbyists where the back of knees, underarms, the bottom sides of chairs and tables, the bottom sides of the roofs, or even the tops of sculpture’s heads (very common problem) have been completely forgotten.ĭO NOT FORGET about proper overlap: every shot needs to overlap with the next in at least 60% (and 80% or more is even better).Ī post with advice on taking images for photogrammetry scan.ĪVOID panoramic shots (where the camera stays on the tripod, and you rotate only the camera). And every point of every surface needs to be seen in at least 2-3 images, taken one straight and two from a slight (10°-15°) angle to surface. Every side of the scanned object needs to be shot: back, top, underneath, inside, etc. On the middle and close-range shots, we need to remember about ALL surfaces. That is why the intermediary step is necessary. The feature (tie point) detection algorithms are not able to recognize a dot in one image and a big coin in the other images. On the far-range images, a coin looks like a dot, and in the close-range images, the coin is seen with clear details. The mid-range shots connect the far distance loop and close-range images. Next is the mid-range and close-range shots: if the first loop is at 3m away from the object, the mid-range is at 1.5m and the close-range is about 50cm. And this “frame” will be used for alignment and depth calculation of the more close-range shots. These images give the photogrammetry software a “basic frame”. For better results, you can make more loops from different elevation levels. 36 images), where the whole object fits in the image. Good scanning practice: at least one loop around the object in 10-degree increments (approx. You should have about 3 to 5 meters of available space around the object, and for the close-up shoot, you’ll need to get to about 50cm from the object (for objects up to 3 meters in height). It is good to have enough moving space around the object you are planning to shoot.
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