Photogrammetry - Data Collection Tutorial

Created by Jack A. Biggs

What is photogrammetry?

Why use or implement photogrammetry into academic research?

What are the data used in photogrammetry?

Collecting the data (taking the photos)

Photos used in photogrammetry must be taken in a specific way and must meet a certain set of criteria:

The number of photos – there is no set number of photos required to create an accurate 3D model

Camera positioning and framing the object – not all models will be of isolated objects, but can be of entire buildings, facades, or interior spaces (solitary objects are the focus for this series)

Photograph overlap - photos taken in sequence should overlap by at least 60% - if there is insufficient overlap, the model will not build correctly or at all (see both the above and below illustrations)

Frame 1 - solid line (assume all are at same height)

Frame 2 - dashed line

Frame 3 - dotted line

Passes or rotations of photos – to get the best models more than one rotation or pass of photos around the object is required

Adequate and appropriate lighting – for the best photo and model results, lighting is extremely important

Minimize shadows – shadows on the object can create permanent dark spots on the model if they are most of the photos

Monopods vs tripods – deciding to use a monopod vs a tripod for photo capture depends partly on personal preference and partly on what and how you’re shooting – these also slightly affect how the model is processed in the Agisoft program

Monopods

Tripods

Using a turntable – turntables can create stability when taking pictures and are especially useful when a backdrop is present

Camera Settings

Focusing the camera

Use a fixed lens – avoid using a lens that has a zooming function

Shoot images in both RAW and JPEG (or PNG) – RAW files can be thought of as “digital negatives” – they cannot be used directly as an image, but they hold all the data to make an image

Use a remote – using a wireless or wired remote to take the photos is easier and it reduces the amount of shaking caused by pressing the capture button

Avoid the built-in camera flash – make sure to turn off this feature and only rely on the lighting setup you constructed


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