top of page

​

3D - Photoscans

I used Metashape to generate high-polygon models of the below trees. The 16bit 16k textured model, constructed from photos, was processed down to a detail that would run in a real-time engine (like Unreal). This was done by de-lighting and projecting it on to a carefully UV mapped low-poly model with 8k PBR textures (albedo, roughness, normals, ambient occlusion, height & cavity maps).

​

Amazingly; The below viewer runs in a web-browser so you don't need to download & install anything to look around the model in realitime (even on a phone). Using the menu (bottom right) you can even view the individual maps used to make this PBR (physically based render) material, so you can see a better material response from the asset.

​

​

Model Notes

Apart from the above model being an interestng shape, it was also a good test of the camera's dynamic range. Trying to capture quality textures on the interior and exterior of the tree without losing detail in the highlights or shadows was really tricky. Before shooting the 200 images for this model I took a few test images from the brightest & darkest areas to choose an average setting, with a slight bias towards longer exposures, so as to best levarage the camera's sensitivity to light. 

​

Reference

When capturing a tree like this I take lots of photo reference of the rest of the tree for reconstruction of the full tree later on. My intention here is to import this final model into Spedtree to make the top part of the trunk, upper branches and foliage. As well as a full image of the tree from multiple angles I take close-ups of the leaves and several angles of the upper branches for shape and texture reference. 

​

​

Equipment

I have gradually been refining the gear I use to shoot these exterior assets. Here is a list of the things I use currently. Since I travel to capture some of these assets I have carefully chose most items to be the lowest possible weight. This complete combo currently totals 3.3Kg (7.3 lbs), or 2.1Kg (4.7lbs) without the laptop.

​

  • Camera: Sony A9 + Gitzo L-bracket (<750g)

  • Lens: Sony 40mm G (173g)

  • Tripod: Manfrotto BeFree Carbon + MSQ6T (<1.1Kg)

  • Laptop: Acer Swift Edge (<1.2Kg)

  • Remote: Sony RMT-P1BT (35g)

  • Calibration: Calibrite Colorchecker passport 2 (80g)

​

Notes:

  • A higher resolution camera would provide slightly improved 3D models & textures

  • Mirrorless recommended (if possible) due to superior live-view AF and sesnor stabilization

  • If scanning interior objects look into a cross polarized ring flash setup, to drastically reduce reflections

  • I chose a 40mm prime lens because: The focal length is a good sweet spot, image quality is hight, it's small / light

  • I chose the tripod because: It's strong, versatile, small / light and has an "Arca Swiss" compatible head

​

Camera Settings

To achieve the highest image quality (and thus 3D models) as possible aim for these settings:

 

  • Lowest ISO value - For the lowest signal noise / cleanest images

  • Smallest "realistic" Aperture (highest f-number) - For greatest depth of field (most range in focus)*

​

* = Avoid smallest apertures (like f/22) to avoid diffraction (softness)

​

Keeping ideal ISO & aperture values will be a constant struggle when shooting hand-held due to available light forcing slower shutter speeds where camera shake will become a problem. If shooting on a tripod you can more easily achieve the best ISO and aperture values becasue you can use longer shutter speeds without having to worry about camera shake. To further guarantee this I also use a remote shutter. 

​

Ideal Conditions

The best weather for shooting exterior photogrammetry is a considently overcast cloud. This will provide flat lighting with soft shadows that will be much easier to remove later. Here are some things to avoid if you can:

​

  • Direct sunlight - this will give hard shadows and high dynamic range, which is very difficult to remove later

  • Changeable light - this will give different lighting between each photo, which is difficult to balance and stitch

  • Wetness - this tends to make everything dark, patchy and reflective. All terrible for photoscanning)

​

This all makes photoscanning extremely picky with weather and can be frustrating when you are on a schedule.

​

bottom of page