Having found a fantastic Script for dividing up terrain from user batFINGER
within this post - blender.stackexchange.com/questions/80460/slice-up-terrain-mesh-into-chunks/133258
import bpy, bmesh from bpy import context from mathutils import Vector # bounding box helper methods def bbox(ob): return (Vector(b) for b in ob.bound_box) def bbox_center(ob): return sum(bbox(ob), Vector()) / 8 def bbox_axes(ob): bb = list(bbox(ob)) return tuple(bb[i] for i in (0, 4, 3, 1)) def slice(bm, start, end, segments): if segments == 1: return def geom(bm): return bm.verts[:] + bm.edges[:] + bm.faces[:] planes = [start.lerp(end, f / segments) for f in range(1, segments)] #p0 = start plane_no = (end - start).normalized() while(planes): p0 = planes.pop(0) ret = bmesh.ops.bisect_plane(bm, geom=geom(bm), plane_co=p0, plane_no=plane_no) bmesh.ops.split_edges(bm, edges=[e for e in ret['geom_cut'] if isinstance(e, bmesh.types.BMEdge)]) bm = bmesh.new() ob = context.object me = ob.data bm.from_mesh(me) o, x, y, z = bbox_axes(ob) x_segments = 2 y_segments = 2 z_segments = 1 slice(bm, o, x, x_segments) slice(bm, o, y, y_segments) slice(bm, o, z, z_segments) bm.to_mesh(me) bpy.ops.object.mode_set(mode='EDIT') bpy.ops.mesh.separate(type='LOOSE') bpy.ops.object.mode_set()
I'm then trying to make use of it in combo with BlenderGIS
Cutting up the heightmap works well, but when I try and layer sat image tiles (already divided up within QGIS) over the top, I notice there is a tiny anomaly on all the edges - a gap to some extent. which it seems to be trying to fill with a different part of the image - which stands out.
When posting about it on BlenderGIS - github.com/domlysz/BlenderGIS/issues/172
It was noted that an additional rows + 1 and columns + 1 might be added so borders overlap.
Not being a Python wiz just yet, can anyone help me understand the tweaks required to adjust the above script to potentially handle the gap issue?
Update - 18/05/19
So one thing I also noticed was a loss of data when importing my heightmap (.asc) into blender, here is the header detail on asc -
When importing into blender I expected 1250 faces along one edge - but in fact it seemed to lose one, and only had 1249:
This might not be a huge issue, however when I then run the script to split into 4 x 4 - dividing 1249 by 4 seems to prompt the faces to be split into 3 sections of 313 x 313 (rounding up) but the edge faces are squashed:
Because I thought this might be contributing to the issue I regenerated my square heightmap with dimensions of 10020 mtrs which made following:
so losing 1 face when imported to blender gave me faces of 1252 which cleanly divides by 4, so now my edges look neat:
My next conundrum is that if I shift the objects following the dividing of heightmap using
ob.location = (0, 0, 0)
then I am unable to import jpg sat tiles using BlenderGIS as it returns error 'No Overlap Data'
Clearly it want's the sat tiles to match with the heightmap's converted blender geo location (however it does that within BlenderGIS)?
and if I try and import the sat tiles at the heightmaps imported location: Vector((644784.5, 4979542.0, 0.0))
perhaps shifting all 16 tiles to the origin will resolve that - but I'm unsure how to move all of them in one batch move?
I'm also wondering if I should just try laying the sat images over the divided heightmap sections using default UV editor / texture config, rather than relying on BlenderGIS custom import feature, as maybe the Geo location element is confusing things? I think I tried one tile like that, but had other issues getting it to lay over terrain without the texture falling through the mesh.