[Qgis-user] Upsampling TIN

[Falk Huettmann]

Hi,
I agree with Barend and Nicolas here.

It's a typical and essential question that we get all the time, like,
can we re-grid and subsample pixels ?
=>You can, technically, but you stay just within the same data,
and thus, create nothing new or meaningful.

In other words, it should not be done.

There is a lot wrong with re-sampling, gridding, within DEMs, with merging
grids,
reprojecting and interpolation surfaces. And GIS techs are pretty guilty of
that,
so are their supervisors.
The tools we provide should point that out clearly and not allow for it.

Key to those questions remain 'ethics', metadata of course (!) and then
always a comparison as a benchmark for
accuracy and to see the actual gain of such re-samplings.

(but let's agree that TINs are only one way of getting a surface, often not
the best one,
when compared to the 'truth'. Playing around with them for best output is
not a bad idea)

  Very best
    Falk Huettmann




On Fri, Oct 4, 2019 at 4:00 AM Nicolas Cadieux <nicolas.cadieux at archeotec.ca>
wrote:

> Hi,
>
> You cannot invent new data between point without doing an interpolation.
> Your choice of interpolation will determine the quality of this data.  The
> only way I can think of is to create a raster from this TIN.  Then,
> resample (re-interpolated) this raster with a finer pixel and then make a
> new TIN.  This may create a finer TIN but this will significantly alter the
> original data.  You would need to evaluate the results and keep a backup of
> the old files.
>
> Alternative, I would try with Mesh Lab.  It’s open source and probably has
> Mesh densification methods that would be more adapted.  Cloud Compare also
> has interesting algorithms.
> Nicolas
>
> > Le 4 oct. 2019 à 03:40, joolek <joolek.o at gmail.com> a écrit :
> >
> > Hi Experts,
> >
> > I've tried so many software's without success.
> > Is it possible to upsample existing TIN? What I mean is for example
> divide each triangle into two for example. Not interpolation but somehow...
> subdivide or add more vertices between existing one?
> > Thank you for all your time
> > J
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