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--- groimp-platform:pointcloudtools [2024/11/11 18:02] – gaetan
+++ groimp-platform:pointcloudtools [2024/12/06 12:04] (current) – [Point cloud tools] gaetan
@@ Line 26: / Line 26: @@
 To use the tools in RGG you should import the following packages:
 <code java>
-import de.grogra.pointcloud.groimp.*;
-import de.grogra.pointcloud.groimp.PointCloud;
 import de.grogra.pointcloud.objects.impl.*;
 import de.grogra.pointcloud.tools.Tools;
@@ Line 33: / Line 31: @@
+===== Local transformation =====
+It is key to understand that in GroIMP each node have a local transformation, and the global coordinate of a node depends on the resolution of all previous local transformations from its parents in the graph.
+For point clouds nodes, it means that two point clouds with points that have the SAME coordinates, might be displayed at different global coordinates. The coordinates of Points are local by default. For instance, the two following point clouds are imported from the same file (and thus have the same local coordinates):
+{{:groimp-platform:pc_relativepos2.png?200| PC F}} {{ :groimp-platform:pc_relativepos1.png?200|F PC}}
+The first image results from //PointCloud F// and the second from //F PointCloud//.
+It is possible to force a point cloud to have global coordinates by moving it to the root of the graph and transforming it with its globalTransformation with :
+<code java>
+PointCloud myPC = ...;
+Matrix34d transfo = de.grogra.pointcloud.utils.Utils.getGlobalTransform( myPC);
+Matrix4d localT = myPC.getLocalTransformation();
+myPC.setTransform( transfo.transform( localT ) );
+[c:PointCloud ==> ^c;]
+</code>
 ===== Split by plane =====
@@ Line 123: / Line 140: @@
 === Output ===
+Point clouds added to the Project graph root:
+{{:groimp-platform:pc1_merge1.png?200|Before merge}} {{ :groimp-platform:pc1_merge2.png?200|After merge}}
+Point clouds with local transformations (as part branch of Nodes with transformations).
+In the following example, the two point clouds are added each after a F build by the following code (where //PC1// and //PC2// are the Point cloud nodes:
+<code java>
+Axiom ==> F PC1 F PC2 ;
+</code>
+In that example, the points of PC1 are translated by the //F// Node, but their local coordinates do not include this translation. Similarly, the points of PC2 are translated twice, once per F.
+If we merge the //RED// point cloud (PC2) into the //BLACK// one we have the following result (the points of PC2 are translated only by the first F):
+{{:groimp-platform:pc2_merge1.png?200|Before merge}} {{ :groimp-platform:pc2_merge2.png?200|After the merge}}
 ==== Cluster ====