insidepoly has trouble with points at the boundary

[kilir]

For some grain maps, checkInside does not return the correct values when using setMTEXpref('insidepoly',true) when used with 'includeBoundary'. However, this does not occur on all maps and it always is the side with the largest X-values of vertices of grains. No issue with inpolygon, setting setMTEXpref('insidepoly',false).

Example:

load('grains.mat')

setMTEXpref('insidepoly',true)

plot(grains)
hold on
plot(grains(grains.isOuterBoundary('delta',1)),'FaceColor','k','lineColor','w')
hold off


setMTEXpref('insidepoly',false)

plot(grains)
hold on
plot(grains(grains.isOuterBoundary('delta',1)),'FaceColor','k','lineColor','w')
hold off

It seems that using a "much" larger tolerance might help

mtex/extern/insidepoly/insidepoly.m

Line 127 in 876336f

ontol = 1e-9*max(Pxmax-Pxmin,Pymax-Pymin);

but however, than points at the boundary seem to be always inside - even if not desired.

grains.zip

[kilir]

It seems that the vertices of the map show some steps below what boundary(x,y,1) is able to capture within tolerance.

[kilir]

It seems the dataset has unevenly spaced coordinates, hence the tiny steps in the grain map

Compare before-after fixing positions

Data kindly provided here: #2525 (reply in thread)

load('ebsd.mat')
ebsd = ebsdS_crop;

format long
yu = unique(diff(unique(ebsd.y(:))))
xu = unique(diff(unique(ebsd.x(:))))
% ok there are rounding differences at the subatomic level

exOld = ebsd.extent

pCo = ebsd.plottingConvention;

%% test as is
ebsd = ebsd.gridify;
grains = ebsd.calcGrains;

%make sure the fast method is used
setMTEXpref('insidepoly',true)

plot(grains)
hold on
plot(grains(grains.isOuterBoundary),'FaceColor','k','lineColor','w')
hold off
mtexTitle('not OK')

%% fix positions

% actual step Size
dP = ebsd.dPos;

% probably what should be the step size
dP = round(dP,3);

% new coordinates
[D1 D2] =  size(ebsd)
[xnew ynew] = meshgrid(linspace(dP,D2*dP,D2) , linspace(dP,D1*dP,D1));
posnew = vector3d(xnew,ynew,0);

% eventually move to the old cropped positions / start
exStart = round(exOld,1);
posnew = posnew + vector3d(exStart(1),exStart(3),0)

% set new positions
ebsd = ebsd(:);
ebsd.pos = posnew;
ebsd = ebsd.updateUnitCell;

% check
dPnew = ebsd.dPos

ebsd.extent

%% test again
ebsd.how2plot = pCo;

ebsd = ebsd.gridify;
grains = ebsd.calcGrains;

setMTEXpref('insidepoly',true)

plot(grains)
hold on
plot(grains(grains.isOuterBoundary),'FaceColor','k','lineColor','w')
hold off

mtexTitle('OK')