Creating TIN Surface with only 3 points

[EAguayoDQXES]

What is the minimum number of points required to generate a TIN surface with contours? I have had no issues creating other files using 4 or 5 points (from a txt file). On this particular project there is only three points of data to work with and no surface is being generated. Any suggestions or help will be appreciated, thanks!File with 3 ptsEx file with 4 pts

[Pointdump · Accepted solution]

Hi @EAguayoDQXES,
Welcome to the Autodesk Forums.
Both sites look like they have deep excavations, so those few points are useless. But if your heart is set on it, create 3 Feature Lines and add extentions until the boundary looks like what you want. Or buy a drone and fly the site. 
In what part of the world is your project? There's lots of good free LiDAR elevation data out there.
Dave

[EAguayoDQXES]

Thank you! Both sites are landfills and these contours are projected underground groundwater elevations based off of the depths of on-site water wells, no cut-fill work. I will make the feature lines like you suggested as a work around, thanks!

[neilyj666 · Accepted solution]

3 points are indeed the minimum but the algorithm doesn't always work as expected with minimal points.

Simple lines added as breaklines usually solves the problem but when extrapolating from sparse data points be wary of too much reliance on the results. This could be an issue if groundwater appears where none was predicted.

[rl_jackson]

@neilyj666 "This could be an issue if groundwater appears where none was predicted."

That's why there are (design) codes, for this sort of thing. SHWT is a floating #. It's pretty hard to design an infiltration trench if SHWT is at EG.

I'd certainly recommend the OP get more data based on the site size. IMO

[neilyj666]

I'm not familiar with SHWT but if ground water was at EGL then infiltration wouldn't be effective...😉...you can never have too much Ground Investigation data