Edge Length and Face Normals in Blender 3D

Edge length, area and angles
Face and vertex normals

Resources

When mesh editing and making models it's often the case that the size of a particular element needs to be determined, not just its orientation. Blender provides two sets of utilities for determining this, they are "Numerics" and "Normals", both of which can be used to display mesh properties useful during the process of making any type of content, real-time or real-world.

A basic understanding of Blender and how to use the application is assumed and necessary for the user to get the most from the following material.

Edge Length, Edge Angles & Face Area ^

There are three main considerations to keep in mind when using the "Numerics" sub-system in Blender. First, numerics only appear when in Edit mode. Second, they appear based on active selections only, that is, they appear only when a particular element or groups of elements are selected, be that a face, edge or collection of both. And third, the 'unit' of measurement is based on Blenders global "Unit" sub-system, that is, the format depends on the choice of 'Unit' and 'grid scale' being used, i.e. "Metric", "Imperial" or "None". For example, using the default 2x2x2 cube and a scenes standard grid set-up, "Edge Length" would be shown as "2m", "2.187yd" or "2.000", as would "Face Area" (surface area), similarly displaying as "4m", "4.374yds" or "4.000". The exception are "Edge Angles" which always display in 'degrees' (0° - 360°).

To activate these element options make sure the mouse cursor is in the 3D view and press "N" to open the "View Properties" tool bar (shown below). From here scroll down to the sub-section titled "Numerics" and select any single or combination of options of "Edge Length", "Edge Angle" or "Face Area" by clicking the associated checkbox.

Selecting the "Edge Length" option to activate measurement values on edges - note: the actual numerical value is determined by the measurement system currently active in "Scene" properties

Selecting the "Face Area" option to activate associated measurement value

Selecting "Edge Angles" to show angles of incidence between selected elements

Face & Vertex mesh normals ^

As with the "Numerics" sub-system discussed above, "Normals" also have a number of considerations that need to be kept in mind when using the parameters. First, normals are only visible whilst in Edit mode. Second, their visibility is not selection dependant, they display at all times so long as the property is active. Third and allied to the previous points, they are displayed at all times irrespective of "Wire", "Solid" or "Textured" "Viewport Shading" mode. Forth, normals are displayed per individual mesh so several objects would need the setting activated per each. And fifth, normals can also have their length altered to make them easier to see on larger meshes or where the user is some distance from the object.

To activate mesh normals, make sure the mouse in over the 3D view and press "N" to open "View Properties". Scroll down the toolbar to the sub-section titled "Normals" and click the checkbox for either/or/both "Face" and/or "Vertex" normals. Additionally to change the length, either select and type a value or LMB+drag the text field "Normal Size: 10cm" - N.B. the 'unit' indicated varies depending on whichever global measurement system is currently being used, for example showing "0.10", "10cm" or "3.94"" respectively for one of "None", "Metric" or "Imperial" measurement.