Exercise 4 - Digitising field samples

Contents

Exercise 4 - Digitising field samples

Deadline

The following exercise is to be completed prior to the final semester presentation.

Deadline

A summary of the methodology as well as numerous tips and tricks can be found in the Small object SfM photogrammetry and Foldio360 Tutorial pages, which should be explored as part of the open-ended exercise below.

Exercise

  • Whilst out on a fieldtrip, collect at least one (1) sample in which any given dimension falls between 5 and 15 centimetres;

  • Write down coordinates of the exact sampling location, fill out the sample metadata form in full (i.e., those fields related to the sampling, not yet processing);

  • When back, process the collected sample and create a to-scale 3D digital hand-sized sample model without artefacts using the automated photography light box procedure.

  • Finalise the sample metadata form and submit/discuss it with the course responsible. This include the SketchFab ID which is only obtained after the submission has been quality controlled and the model has been uploaded to SketchFab.

Bulk sample density

Seeing as your digital model is 1:1 scaled with the real sample, any idea on how to calculate its bulk density?

Metashape volume measurement

Metashape provides a built-in feature to determine a model’s volume (Tools/Mesh/Measure Area and Volume…). Be careful, though, as this calculates the total volume of all closed surfaces/meshes in your project. The calculated volume is furthermore given in m3 - so make sure to apply the correct conversion. Better yet, use some handy Python code that calculates the volumes in cm3 instead.

Model annotation and interpretation

The same tools used for interpreting and annotating digital outcrop models (DOMs) can also be used for hand-sized digital models. Have a look at the geomodelling tutorial to get started.