Research on Photogrammetry

After attending Animex 2016 last week, a term / method which was frequently mentioned during the festival was “Photogrammetry”, most memorably used as part of the Moving Picture Company talk on the creation of the environment in The Martian.

This was a term that I was not very familiar with, as a result, it was my aim to learn more about this technique.

What is Photogrammetry?

Photogrammetry is a technique of using multiple over-lapping images / photographs to recreate 3D environments, scenes or objects.  With the availability of free or relatively inexpensive processing software, this method has became increasingly more popular over the past decade.

According to http://www.photogrammetry.com, there are two types of photogrammetry, Aerial and Close-Range.

Aerial Photogrammetry

Aerial photogrammetry usually uses a camera which is attached to an aircraft, which is adjust to point vertically towards the terrain below.  The required overlapping photos of the environment are captured whilst the aircraft flies above, in preparation to be processed accordingly.

Examples of Aerial Photogrammetry

Close-Range Photogrammetry

In close-range photogrammetry , the camera is commonly  hand-held but usually on a tripod. This type of photogrammetry is usually used for drawings and 3D modelling within fields including biology, engineering, forensics and film.  This type of photogrammetry is also known as Image-Based Modelling.

Examples of Close-Range Photogrammetry

https://sketchfab.com/abbyec?utm_source=oembed&utm_medium=embed&utm_campaign=3e16d5a819c4419dba79999889e83fd2

Photogrammetry used in the Games Industry

The Vanishing of Ethan Carter by The Astronauts team is one of only a few games to date to use photogrammetry in creating photo-realistic assets / environments, however not using them in a photo-realistic way.

Using this method removes such elements as tiling textures and overly smoothed edges to create a much more believable / realistic environments, as they are in fact, reality.  Instead of modelling each asset using 3D modelling software, the team from The Astronauts went out on location and took 360 degree photographs from multiple angles of actual objects and terrain.

The photographs were then imported into software designed for photogrammetry called Photoscan by Agisoft (http://www.agisoft.com/).  This software analyses these images and matches each feature of the object taken from all angles, resulting in vertices being created in a 3D space which represents the real world object.  These vertices are then connected to complete the mesh, lastly projecting pixels from the photographs taken to produce a texture upon the 3D model.

image

The Vanishing of Ethan Carter features a statue created using the same method.  The footage below shows the software calculating the original position of cameras from every photo to produce the vertices require to complete the 3D model.

photo

The final statue model can be explored using the link below.

https://p3d.in/e/xtwH3+spin+shading,subd-hidden+load

A disadvantage of using this method is a scanned image can result in meshes containing between 2 and 20 million triangles, a number usually seen for a complete game rather than a single asset.  This requires an immensely skilled artist that can edit and optimize topology to create a more usable low poly mesh, as well as adjusting UV templates to maximize the percentage of used space within the texture. However, the results still demands a lot of RAM but is ever increasing in modern technology.

A step-by-step guide of the process described above can be found here:

Sometimes a game requires to go beyond photo-realism, which can only be achieved by creating a visual style using stylised lighting and post-processing, also by mixing assets created using photogrammetry with those created using traditional 3D modelling software and techniques.

Finally, as described by the people at The Astronauts:

“And the end of the day, photogrammetry is a tool. Nothing less, but nothing more. It’s still up to designers and artists to decide what kind of world they are creating, and on what journey they want to invite the players.”

 

 

 

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