I am fairly new to sketchup, so maybe what I am attempting is beyond my skills, if so please say as I think I could use Sketchup in 2D mode to do the same thing in several 2D drawing and sections. But a single integrated 3D model would be so much better and help me think things through. I am using SU Make 2017.
My overall project is to create a model of my cottage from architect drawings for use in repairs and improvements. As part of this I am trying to use sketchup to model a non-planar polygonal ground surface abutting buildings and an inclined, bent trenches including some french drains with pipes in them around the buildings and to a septic tank and soakaways.
As part of this I have already managed to create TIN-based terrain models from LIDAR air survey data (DSMs and DTMs). Here is a post on that attempt: Importing UK LIDAR DTM data with decimal elevations as a terrain model. Unfortunately while supplying quite a lot of useful and seemingly accurate heights it seems to me to contain too many artefacts (DSM-based), or reflect too much smoothing for direct use (when DTM based), though I could be wrong.
I also have an architects survey which gives land levels relative to ground floor level where they abut the house. So probably enough information to create a reasonably accurate surface close to the house given my knowledge of the actual topography.
I have also traced and created the ground floor walls from an arctitects plan, and a 3D model of our new shower room and utility room and lobby. As an initial expoloration of land surfaces, I have created planar, rectangular, inclned surfaces round the house to roughly model the ground levels, but predictably they don’t model the places the terrain is non-planar well enough, and don’t join together as they have to be tilted differently and are rectangles. Not only aer certain slopes needed for correct functioning, but UK building regs require that pipes are normally laid at least xcm below ground and with a slope between certain limits.
Having read some help files and some posts I can see two possible ways of approaching the problem, though I do not know how to do it in detail. I may also be missing an obvious third or forth approach!
Both start with setting up construction points at places where I know the height above site datum.
Drape a TIN over the construction points and around the house, and indent the ditches into it. To model the ditch sides sensibly you would seem to need a reasonably fine mesh, maybe 5cm - would this not make the model very big? The drainage work will probably cover 0.2 acres or so. But then how do you get it to deform only to the degree necessary to model a slightly to moderately non-planar surface? And how do you create an inclined ditch with bends in it?
Create a single, non planar, irregular polygonal vector surface around the houses, and over the construction points, and push it down or break it to model the ditches. I am not sure this is even possible in sketchup, though I know there are tools for bending and twisting etc surfaces. I am not sure what tool you would use to create a bent inclined ditch in it…
If someone would not mind answering some initial queries I would be very grateful. Is what I am attempting feasible given a reasonable degree of persistance? If it is broadly what approach would you suggest to execute it, and what additional tools should I use?
Many thanks for any help you can give in anticipation.