Glossary of terms

Histogram - A diagram that graphically represents the quantity of points that fall within equal ranges with rectangles that increase in height as more points fall within that range.

Mesh - Triangular polygons are generated between the points of a point cloud until a ‘solid’ mesh is created. The point cloud become the vertices of the mesh.

Metadata - Information that describes other data.

Morphometric parameters - Quantitative measurements that can be used to describe an object’s form. This includes measurements you will already be familiar with (length, width, volume), but can also include parameters like ‘Roughness’ or ‘Curvature’. Morphometrics only take into account the shape of the 3D surface.

• Roughness – Morphometric parameter calculated by CloudCompare in the following way – “For each point, the 'roughness' value is equal to the distance between this point and the best fitting plane computed on its nearest neighbours.”

• Curvature - Morphometric parameter calculated by CloudCompare in the following way - “The curvature at each point is estimated by best fitting a quadric around it based on its nearest neighbours.”

Outliers – Data points which fall outside the normal range of the majority of the other points in the point cloud.

Point cloud – Calculated points in three-dimensional space produced when a digital imaging technique measures and records the surface of an object; each point is defined by a set of coordinates on the X, Y and Z planes.

Scalar Field - As defined in the CloudCompare manual, is ‘a set of values (one value per point)’; CloudCompare allows a value associated with a point/vertex to be displayed as colours, have filters or basic math operations applied to them.

Shaders – Tools that render the appearance of the surface based on a number of factors, including lighting position and transparency, view position, material properties, and shape of the 3D surface.

Texture - A photorealistic flat image that can be ‘draped’ over the 3D mesh to give it a more realistic appearance. A texture can also be created independently and applied to a 3D model with no colour information

Transformation matrix - A matrix is an array that, in this case, dictates how the mesh needs to be mathematically rotated and translated to align with the plane. The first three columns correspond to how the points should rotate in three dimensions, while the fourth column corresponds to how much and in what direction the mesh needs to slide, or translate.

Trivet – A type of kiln furniture used to keep unfired vessels apart at the Parker-Harris Pottery site.