3js main job is to show things, it has less codes to make things. Someone has posted similar question recently 3D Mesh from cloud of points maybe you could employ similar hack to use THREE.ConvexGeometry? so, basically,
- add the point way below everything (think center of the earth, but not to scale),
- normalize the distances from your points to that center,
- make ConvexGeometry out of that,
- remove all the faces that include the point added at step 1,
- replace vertex coordinates with the original values.
Another option would be just warping Plane(Buffer)Geometry, of course, assuming you have xz data in regular intervals, for example, or if TIFF refers to heightmap texture (in which case you could also just write some 5 lines ShaderMaterial to render it).