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Photogrammetry

The photogrammetry process is used to provide high complexity, extremely realistic virtual sets from a series of photographs. We are introducing a new pipeline to speed up and increase the quality of Photogrammetric set creation for real-time virtual integration.

Process

This process for creating scenes will be adaptive to the level detail you will want to achieve.

  1. Photographing a location
  2. Point cloud generation, dense mesh solving with Agisoft Photoscan.
  3. Automatic retopology and UVs in Modo, Mudbox or ZBrush.
  4. Texturing geometry
    1. Via automatic texture projection in Photoscan.
    2. Via hand painting in Modo or Mari.
  5. Optimization with 3D software.

1. Photography

This initial step is very crucial, as it can set the tone for the entire project. Things like, camera, shooting style, time of day and weather can all affect the outcome. In all of our tests, we have been using Prosumer cameras, Nikons, Canons, and Panasonics with resolution of 4K+. Tests have yet to be done with Professional film cameras.

Camera Settings

  • Lock shutter speed, fast enough to eliminate motion blur.
  • Use a small enough aperture to keep everything in focus. An f-stop closer to f11 – f16 will be optimal, sometimes the lowest aperture, like f22, can cause defraction making images overall less sharp.
  • Lock ISO to a low setting (ex. 160), to avoid grain.
  • Lock exposure to desired look.
  • Use a neutral white balance, making it easier to color correct later. If you’re shooting JPEG this is critical, if you’re shooting in Raw, it can be fixed later.

Procedure

  • The method to which the photos are taken also has a great impact on the results. When capturing texture data you will want to have views from all angles. Usually a method of orbiting objects and walking parallel to walls while shooting with 20-40% overlap, will provide the necessary parallax needed to generate a point cloud. Parallax is needed when solving for small details like cracks in brick, slots in wood, or other rough textures. It also helps provide optimal texture coverage, so that no textures are stretched or left out.

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  • Shooting stills or shooting video and extracting every nth frame, have no difference on the quality of the solve. Stills will generate higher resolution images. Shooting stills on a burst mode is a good method for shooting when light is abundant.
  • You will want coverage of everything from the ground to sky.
  • When you shoot also has an effect on point cloud solve, because natural light is not a constant. Depending on the time of day, you will want to shoot to preserve equal lighting from beginning to end.

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2. Photoscan solving

Photoscan, in recent releases has massively upgraded their solving capabilities. Making it an essential tool for a photogrammetry pipeline. Using version 1.0.4 and up, we will go over the steps to achieve a great solve. On top of accuracy, Photoscan is offered at a competitive price, download the Standard edition for Agisoft’s website.

3. Retopology

Mudbox and Zbrush both have robust automatic retopology tools, while Modo can be used to do manual retopology. These programs can also properly lay out the UVs.

4. Texturing

Photoscan is capable of reprojecting textures onto simplified mesh.

Modo and Mari can also be used to paint texture detail, or touch up an automatic texture.

5. Optimization

This step is sometimes needed to add in transform names to objects, or break up the set into areas.