From 49028dd1232fb758ba3613ef71eccadd4c7681eb Mon Sep 17 00:00:00 2001
From: Jean-Yves TINEVEZ <tinevez@pasteur.fr>
Date: Tue, 30 Jun 2020 14:23:59 +0200
Subject: [PATCH] Compute perimeter 3d.
---
RunExample.m | 12 +++++++++---
src/perimeter3d.m | 14 ++++++++++++++
2 files changed, 23 insertions(+), 3 deletions(-)
create mode 100644 src/perimeter3d.m
diff --git a/RunExample.m b/RunExample.m
index c7407a1..d536ed8 100755
--- a/RunExample.m
+++ b/RunExample.m
@@ -147,11 +147,14 @@ for i = 1 : n_objects
o = objects( i );
area = area3d( o.boundary );
+ perim = perimeter3d( o.boundary );
+
+ objects( i ).area = area;
+ objects( i ).perimeter = perim;
uncorr = struct();
uncorr.area = polyarea( o.boundary(:,1), o.boundary(:,2) );
-
- objects( i ).area = area;
+ uncorr.perimeter = perimeter3d( o.boundary( :, 1:2 ) );
objects( i ).uncorr = uncorr;
end
@@ -181,7 +184,10 @@ for i = 1 : n_objects
o = objects( i );
P = o.boundary;
- patch( P(:,1), P(:,2), P(:,3), o.area / o.uncorr.area, ...
+
+ err = o.perimeter / o.uncorr.perimeter - 1;
+
+ patch( P(:,1), P(:,2), P(:,3), err, ...
'LineWidth', 2 );
text( o.center(1), o.center(2), o.center(3) + 0.5, num2str( i ), ...
'HorizontalAlignment', 'center', ...
diff --git a/src/perimeter3d.m b/src/perimeter3d.m
new file mode 100644
index 0000000..ff98ddf
--- /dev/null
+++ b/src/perimeter3d.m
@@ -0,0 +1,14 @@
+function perim = perimeter3d( p )
+%PERIMETER3D Perimeter of a closed N-dimensional polygon.
+% p can be a N x d matrix, with d being the dimensionality.
+
+ p2 = [ p ; p( 1, : ) ];
+ p_diff = diff( p2 );
+
+ p_diff_2 = p_diff .* p_diff;
+ p_diff_2_sum = sum( p_diff_2, 2 );
+ sls = sqrt( p_diff_2_sum );
+ perim = sum( sls );
+
+end
+
--
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