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[delaunay] Qhull print options (P)

Copyright © 1995, 1997 The Geometry Center, Minneapolis MN


SynopsisMainOutputFormatsGeomviewPrintQhullPrecisionTrace

»Print options

Po
force output despite precision problems
Po
if error, output neighborhood of facet
Pp
do not report precision problems
Pg
print good facets (needs 'QGn' or 'QVn ')
PG
print neighbors of good facets
Pdk:n
drop facet if normal[k] <= n (default 0.0)
PDk:n
drop facet if normal[k] >= n
PAn
keep n largest facets by area
PFn
keep facets whose area is at least n
PMn
keep n facets with most merges

»Po - force output despite precision problems

Use options 'Po' and 'Q0' if you can not merge facets. Option 'Po' can not force output when duplicate ridges or duplicate facets occur. It may produce erroneous results. For these reasons, merged facets or exact arithmetic may be better.

If you need a simplicial Delaunay triangulation, use option 'Ft'. If you need a simplicial triangulation of the original input sites, use 'Q0' . If 'Q0' reports precision problems, use exact arithmetic or 'Po'.

Option 'Po' may be used without 'Q0' to remove some steps from Qhull or to output the neighborhood of an error.

If option 'Po' is used,

»Po - if error, output neighborhood of facet

If an error occurs before the completion of Qhull and tracing is not active, 'Po' outputs a neighborhood of the erroneous facets (if any). It uses the current output options.

»Pp - do not report precision problems

With option 'Pp', Qhull does not print statistics about precision problems, and it removes some of the warnings.

»Pg - print good facets

Qhull can mark facets as "good". This is used to

Option 'Pg' only prints good facets that also meet 'Pdk' and 'PDk' options. It is automatically set for options 'PAn' and 'PFn '.

»PG - print neighbors of good facets

Option 'PG' can be used with or without option 'Pg' to print the neighbors of good facets. For example, options 'QGn ' and 'QVn' print the horizon facets for point n.

»Pdk:n - drop facet if normal[k] <= n

For example, 'Pd0:0.5' does not print facets with normal[0] <= 0.5 . The default value of n is zero. For example in 3-d, 'Pd0d1d2' displays facets in the positive octant. If no facets match, the closest facet is returned.

»PDk:n - drop facet if normal[k] >= n

For example, 'PD0:0.5' does not print facets with normal[0] >= 0.5 . The default value of n is zero. For example in 3-d, 'PD0D1D2' displays facets in the negative octant. If no facets match, the closest facet is returned.

In 2-d, 'd G PD2' displays the Delaunay triangulation instead of the corresponding paraboloid.

Be careful of placing 'Dk' or 'dk' immediately after a real number. Some compilers treat the 'D' as a double precision exponent.

»PAn - keep n largest facets by area

The n largest facets are marked good for printing. This may be useful for approximating a hull. Unless 'PG' is set, 'Pg' is automatically set.

»PFn - keep facets whose area is at least n

The facets with area at least n are marked good for printing. This may be useful for approximating a hull. Unless 'PG' is set, 'Pg' is automatically set.

»PMn - keep n facets with most merges

The n facets with the most merges are marked good for printing. This may be useful for approximating a hull. Unless 'PG' is set, 'Pg' is automatically set.


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Created: Sept. 25, 1995 --- Last modified: see top