From 6ca0ca5fcbbdba3c48aa29489a4f7ddbd0ff6429 Mon Sep 17 00:00:00 2001
From: Jean-Yves TINEVEZ <tinevez@pasteur.fr>
Date: Sun, 26 Jul 2020 12:31:08 +0200
Subject: [PATCH] mesh_to_heightmap: Create a height-map from a mesh.
Brute force, thanks to the power of linear scattered interpolant.
---
src/@deproj/deproj.m | 4 +++-
src/@deproj/mesh_to_heightmap.m | 30 ++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+), 1 deletion(-)
create mode 100644 src/@deproj/mesh_to_heightmap.m
diff --git a/src/@deproj/deproj.m b/src/@deproj/deproj.m
index f76b75a..13c595f 100644
--- a/src/@deproj/deproj.m
+++ b/src/@deproj/deproj.m
@@ -131,7 +131,8 @@ classdef deproj
% Read a PLY file.
[ V, F, comments ] = ply_read( file_path )
-
+ % Create a height-map from a mesh.
+ [ H, min_y, min_x ] = mesh_to_heightmap( V, pixel_size )
end
@@ -144,6 +145,7 @@ classdef deproj
% Returns the cells from a BW image with ridges.
[ objects, junction_graph ] = mask_to_objects( I, downsample )
+
end
end
diff --git a/src/@deproj/mesh_to_heightmap.m b/src/@deproj/mesh_to_heightmap.m
new file mode 100644
index 0000000..26f0fe9
--- /dev/null
+++ b/src/@deproj/mesh_to_heightmap.m
@@ -0,0 +1,30 @@
+function [ H, min_y, min_x ] = mesh_to_heightmap( V, pixel_size )
+%MESH_TO_HEIGHTMAP Create a height-map from a mesh.
+% Of course there are plenty of restriction on the mesh for this to be
+% valid. Mainly: we need the mesh to be so that there is only 1 Z for each
+% X, Y couple. Secondly, the X and Y coordinates need to be positive.
+
+ % Convert to pixel-coordinates.
+ x = V( :, 1 );
+ y = V( :, 2 );
+ xp = x / pixel_size;
+ yp = y / pixel_size;
+ z = V( :, 3 ) - min( V( :, 3 ) );
+
+ % Allocate target image.
+ max_x = 1 + ceil( max( xp ) );
+ max_y = 1 + ceil( max( yp ) );
+ min_x = 1 + floor( min( xp ) );
+ min_y = 1 + floor( min( yp ) );
+
+ % Interpolate.
+ si = scatteredInterpolant( xp, yp, z, 'linear', 'none' );
+
+ % Create elevation on the the grid.
+ [ X, Y ] = meshgrid( min_x : max_x, min_y : max_y );
+ z_im = si( X(:), Y(:) );
+ z_im( isnan( z_im ) ) = 0.;
+ H = reshape( z_im', [ ( max_y - min_y + 1 ) ( max_x- min_x + 1 ) ] );
+
+end
+
--
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