Photogrammetry is taking multiple photographs of an object or environment from various angles and combining them to create a digital 3D model. It is similar to how today’s advanced cameras create a panorama view by combining overlapping images into a 2D mosaic.
Photogrammetry seems new, but it is not. The method of reconstructing objects in the physical world is rooted in principles of perspective and projective geometry, which have been practiced since the late 19th century.
However, with day-to-day technological advancements and innovations in software and aerial photography, the field of photogrammetry has observed tremendous growth in the past few years. Also, the use of photogrammetry has increased manifold.
Today, photogrammetry is used to make highly accurate and realistic photo-textured models of landscapes, archaeological sites, buildings and objects. If you want to know how to use photogrammetry to create 3D models of an object, continue reading!
Capturing the images
Capturing images is a crucial part of the photogrammetry process and needs to be done carefully. For this, you would need a phone or a digital camera of high resolution. Remember, you need to capture every object’s surface in multiple photographs.
That means you need to have a 720-degree image capture strategy. While capturing the images, you will have to go around the object so that later the software you will use to stitch the pictures can recover the exact position of the object’s surface points and create a 3D surface.
Make sure you capture all the textures and features of the object; you must flip, roll over and move the object so that you can take photographs from multiple angles. Also, remember that you need photographs of the object in a neutral environment. Anything not relevant to the object, such as an object or wall behind the object, must not appear in the images.
This is because the software used to create the 3D models will reconstruct every element in the image set. Therefore, it is necessary to blank out the background around the object by placing it in a space with no other entities.
Making the 3D model
Another crucial aspect of photogrammetry is merging the image sets and creating the 3D models. Combining the image sets and creating a 3D model is a five-step process:
- Add individual photos or a folder containing pictures to the software’s interface.
- Align photos. In the second step, the pixels are compared in your image sets to find matches and the software estimate the camera location and 3D geometry from them.
- Build a dense cloud. Once photos are aligned, a sparse point cloud is processed into a dense cloud using the matching pixel, and each pixel will get its exact X, Y, and Z location.
- Build mesh. In the fourth step, the software combines each set of X, Y, and Z points to build a mesh over the model’s surface.
- Build texture. In the final step, the images are combined, and a photo-realistic model of your original object is obtained.
Numerous photogrammetry software can help you convert any image set into 3D models. There is free and paid software; you can choose depending on your project, the features you need, and your budget.
Both types of software provide free trials, allowing you to try the use of photogrammetry before you buy. But, the paid software solutions undeniably produce better 3D models than free options. Sometimes, when you are unable to hide the features around the object, you need software that comes with masking tools that are not provided in free options.
