[Qgis-user] Interpolation Plugin

[Marco Hugentobler]

Hi André

> Now my question is: what does it mean the options "structured lines" and
> "break lines"?

These options have no influence for IDW interpolation, only for TIN 
interpolation.

-structure lines: triangle edges are constrained to line / polygon features 
(e.g. to prevent triangle edges crossing valleys, ridges or contours)

-breaklines: like structure lines. But for cubic triangle interpolation ( 
clough-tocher), the break line is a edge (so not continuously differentiable)
(details in 
http://www.geo.uzh.ch/fileadmin/files/content/abteilungen/gis/research/phd_theses/thesis_MarcoHugentobler_2004.pdf, 
chapter 5)

>And by the way,
> what does the "Distance coefficient" implies?

It's the same parameter as the 'power' (IDW only has one parameter).


Regards,
Marco

Am Samstag, 9. Oktober 2010, um 19.48:23 schrieb ALT SHN:
> Hello List,
> 
> I have a question about the QGIS Interpolartion Plugin.
> 
> I have a line vector representing altitude by means of isolines of 10m,
> covering an area of about 400 square km. I have read scientif paper that
> advices the use of IDW with power 1-3 for hilly topography (thats my case).
> 
> Now my question is: what does it mean the options "structured lines" and
> "break lines"? How can they affect the accuracy of my DEM? And by the way,
> what does the "Distance coefficient" implies?
> 
> Thanks in advance
> 
> André


-- 
Dr. Marco Hugentobler
Sourcepole - Linux & Open Source Solutions
Webereistr. 66, CH-8134 Adliswil, Switzerland
marco.hugentobler at sourcepole.ch http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee