In bitmap editing “to flatten” multiple selected objects/layers means “to rasterize” them to a single bitmap background layer, where they are no standalone objects anymore.
In Figma at
Menu > Object you have introduced the terminological division “Flatten Selection” vs. “Rasterize Selection”.
In bitmap editing software “to flatten” and “to rasterize” are very often synonymous!
I.e. Snagit uses “Flatten selection” exactly in the meaning of “rasterize selected bitmap and/or vector objects into the bitmap background layer”.
So the confusion is perfect for people having worked in design software for 1-2-3 decades, now starting with Figma.
I mean seeing the term “flatten” and “rasterize” side by side, rasterize clearly has the stronger “bitmap connotation”.
But using “flatten” per se is problematic! As it was and still is synonymous in many design softwares and in computer aided design literature. So if you see “flatten” alone, the potential for misinterpretation is very large.
Even if you explore them side by side – as they are in the same section within the “Object” menu – still you may not realize them as complementing/counterpart functions.
Thinking about “flattening” as a term for breaking down certain primitive objects such as oval, rectangle and polygon into pure vector shapes/paths/networks:
Flatten is somehow appropriate as it removed a more structured set of properties (such as coordinates, dimensions, number of points, angles, etc) into pure vector paths, which are just a loose collection of points and connections between them. So in a way they are “flatter”.
But still, I think there are better verbs out there to express that, while avoiding the confusion with “flatten” as in transforming a vector object into a bitmap object.
- Convert to vector shape
- Transform to vector shape
- Break down to vector shape
And please do explicitly not use: “Vectorize selection”. Because that on the other hand may give the wrong impression that it converts a bitmap object into a vector shape by line tracing or similar technologies.