As we are going through the class material I have noticed that in GRASS7
in r.resample.interp method bilinear was changed to linear and bicubic was changed to cubic.
I would like to ask whether it would be OK to change it back for two reasons:
- consistency with 6.4 (minimizes changes required in tutorials, scripts, assignments etc.)
- bilinear interpolation is not linear, (see the relevant text in wikipedia you need to scroll down to find the relevant section)
Also, the change to linear and cubic has created additional inconsistencies in manual pages of
r.resamp.bspline
v.sample
v.drape
which have bicubic or bilinear in the examples and the text, but cubic and linear in the command SYNOPSIS parameters.
Helena
Helena Mitasova
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As we are going through the class material I have noticed that in GRASS7
in r.resample.interp method bilinear was changed to linear and bicubic was changed to cubic.
for the record, there was a discussion about that a while ago [1]. So
probably we will to open this discussion again.
As we are going through the class material I have noticed
that in GRASS7 in r.resample.interp method bilinear was
changed to linear and bicubic was changed to cubic.
Martin:
for the record, there was a discussion about that a while
ago [1]. So probably we will to open this discussion again.
for my 2c wrt interpolations I seem to come across "bilinear" in the world-beyond grass more commonly, and to me it makes more sense.
Is the "bicubic" truly considering x and y separately? i.e. is it actually correct to use the "bi-" prefix with it? If it's more of a buffer operation, cubic might be better.
but whatever is chosen, consistency in use is good to help with the learning curves. I wouldn't object to bilinear + cubic though if each was considered best in its class.
Martin I read the discussion post (I should have mentioned it, I did not realize that the change has been made until now)
to all - please read the wikipedia entry linked in my post (read the whole thing, not just the first paragraph),
"Contrary to what the name suggests, the bilinear interpolant is not linear; nor is it the product of two linear functions.
Alternatively, the interpolant can be written as
So, is there any objection to change it back to bilinear/bicubic? If not I will change it and correct the manuals as well (revert r57279).
Does anyone know if linear/cubic is used somewhere used correctly, I mean in the 1-dimensional sense? I couldn’t find anything like this.
What about renaming G_OPT_R_INTERP_TYPE to G_OPT_R_INTERP_TYPE_2D just in case we would ever need to define separate options for 1 or 3 dimension interpolation?
