Gilbert I have had a look at your dataset with version 5.3.10 I get the same results as you did with 5.2.8 I do not think there is any bug. There is a conceptual problem with the way the house and areas have been drawn in the file surface1.th2 The area water in your terrasse was making use of the already closed line that depicts the house. This is too complicated for Therion I think, as I would have trouble guessing a unique solution if I were filling the areas myself and I did not already guess what answer was wanted. Also the house, terrasse and invisible wall, all defined with 'line wall' do not uniquely define a passage 'inside' and 'outside'. That is why your areas are shaded with odd gaps (the clue is that the missing triangles all project from corners of the above three shapes). I have added some extra lines and separated the house from the terrasse and closed the invisible wall to mostly correct the shading aberrations in the attached file. If you insert it into your sample dataset you should get better area shading. The problem is that the way you have tried to draw the house is not consistent with the way a cave passage wall might be configured. Hence not surprising that Therion has trouble with it. You need a single wall outline. Any internal 'walls' would need to be a different linetype or a wall with '-outline none' set. Hope that explanation is clear. Bruce -----Original Message----- From: therion-bounces@speleo.sk [mailto:therion-bounces@speleo.sk] On Behalf Of Gilbert Fernandes (mailinglist) Sent: Saturday, 29 September 2012 4:55 a.m. To: List for Therion users Subject: [Therion] bug encounter Hello, I have a bug in my (old) release of therion (5.2.8) It's on the drawing of the area (swump area) witch represent a house over a cave. We have a triangle white, I think the software have a problem to calculate the correct surface. I try to split the line (one only line for all the cave), nothing change. It's not a probleme for me. I give it to you to reproduce the bug if it's useful. On the plan, I put the cave upper the house, it's normal, it's to see the cave. Thanks a lot for your work. Gilbert