Re: [osg-users] Erratic intersections with long line segments
Hi, We also created a version with doubles for the project that I'm working on. (The reason for this was that we needed to calculate the derivative of a geocentric terrain given a lat/long coordinate.) It would be convenient for us if this option was given as a cmake flag. I'm pretty new to osg so my question is basically what it never got into the trunk means - was it not a good idea? Why has it been rejected? Regards, David Karlsson Från: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] För Tomlinson, Gordon Skickat: den 15 april 2009 15:51 Till: OpenSceneGraph Users Ämne: Re: [osg-users] Erratic intersections with long line segments Thanks Marcin That's sort of what I was thinking that it had to be rounding, our tiles are localized so YX are relatively small but the Z could be any value range on the earth and seabed, 1million,-1million was over kill for the segment length. Be we will look to go the double route . Thanks again for you reply, Gordon Product Manager 3d __ Gordon Tomlinson Email : gtomlinson @ overwatch.textron.com __ From: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Marcin Prus Sent: Wednesday, April 15, 2009 4:01 AM To: OpenSceneGraph Users Subject: Re: [osg-users] Erratic intersections with long line segments Hi Gordon, we had similar problem here. We were standing exactly at the edge of 2 adjacent triangles in large terrain database and osgUtil::LineSegmentIntersector failed because of internal floating precision. Using doubles instead of floats inside osgUtil::LineSegmentIntersector solved our problems. I've made submission on 18.02.2009 with modified LineSegmentIntersector using cmake flag to set float or double precision internally but it never got into the trunk. You can look at it and create your own LineSegmentIntersectorDbl : public LineSegmentIntersector with double maths inside. Perhaps this will help - it did in our case Best, Marcin Prus Tomlinson, Gordon pisze: HI All I posting this for one of my folks who's is having some erratic results when using a long vertical line segment and the standard osgUtil::LineSegmentIntersector Basically when he sets a line segment up with end X,Y, 100 and start X,Y, -100 , occasionally we fail to get a hit even though we are in the middle of the terrain skin, although moving the X,Y several meters in any direction and we get a hit. If we reduce the Z of the line segment to 500k and -500k this happens less errant fails, if we reduce the Z's to 1k, -1k then we never get a fail, further when we are failing with the intersections if the camera is further away from the intersection the less fails we get, the more we move closer to the intersection point the more fails we get. Our Near and Far clip are fixed, 1 to 10-20k , the terrain skin is stanard OSG geometry, nothing fancy, some lods, but the level and which lod is showing does not seem to be the issue I'm at at a loss to why this may be happening, we are not doing anything out the oridnary in this case that I can think that would cause this erratic behaviour , any one seen anything like this before ? thanks Gordon Product Manager 3d __ Gordon Tomlinson Email : gtomlinson @ overwatch.textron.com __ (C): (+1) 571-265-2612 (W): (+1) 703-437-7651 Self defence is not a function of learning tricks but is a function of how quickly and intensely one can arouse one's instinct for survival - Master Tambo Tetsura ___ osg-users mailing list osg-users@lists.openscenegraph.orgmailto:osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- Marcin Prus Kierownik Projektu ETC-PZL Aerospace Industries Sp. z o.o. Al. Krakowska 110/114, P.O. Box 22 02-256 Warszawa http://www.ai.com.pl tel: (48-22) 846-54-17 wew. 135 fax (48-22) 846-54-18 e-mail: p...@ai.com.pl NIP 522-01-01-817KRS 010025 Sąd Rejonowy dla m. st. Warszawy w Warszawie XIII Wydział Gospodarczy Krajowego Rejestru Sądowego. Wniesiony kapitał zakładowy Spółki wynosi 1 000 000 złotych. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Erratic intersections with long line segments
2009/4/20 David Karlsson david.karls...@foi.se Hi, We also created a version with doubles for the project that I'm working on. (The reason for this was that we needed to calculate the derivative of a geocentric terrain given a lat/long coordinate.) It would be convenient for us if this option was given as a cmake flag. I'm pretty new to osg so my question is basically what it never got into the trunk means - was it not a good idea? Why has it been rejected? The submission wasn't merged as is I don't feel it's appropriate to manage the internal double support as an optional compile, rather we should have two LineSegment compute methods - one using doubles, and one using floats and have a setting to switch between the two at runtime. You needn't even need a separate class for it. Robert. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Erratic intersections with long line segments
Hi Gordon, we had similar problem here. We were standing exactly at the edge of 2 adjacent triangles in large terrain database and osgUtil::LineSegmentIntersector failed because of internal floating precision. Using doubles instead of floats inside osgUtil::LineSegmentIntersector solved our problems. I've made submission on 18.02.2009 with modified LineSegmentIntersector using cmake flag to set float or double precision internally but it never got into the trunk. You can look at it and create your own LineSegmentIntersectorDbl : public LineSegmentIntersector with double maths inside. Perhaps this will help - it did in our case Best, Marcin Prus Tomlinson, Gordon pisze: HI All I posting this for one of my folks who's is having some erratic results when using a long vertical line segment and the standard osgUtil::LineSegmentIntersector Basically when he sets a line segment up with end X,Y, 100 and start X,Y, -100 , occasionally we fail to get a hit even though we are in the middle of the terrain skin, although moving the X,Y several meters in any direction and we get a hit. If we reduce the Z of the line segment to 500k and -500k this happens less errant fails, if we reduce the Z's to 1k, -1k then we never get a fail, further when we are failing with the intersections if the camera is further away from the intersection the less fails we get, the more we move closer to the intersection point the more fails we get. Our Near and Far clip are fixed, 1 to 10-20k , the terrain skin is stanard OSG geometry, nothing fancy, some lods, but the level and which lod is showing does not seem to be the issue I'm at at a loss to why this may be happening, we are not doing anything out the oridnary in this case that I can think that would cause this erratic behaviour , any one seen anything like this before ? thanks /Gordon Product Manager 3d /__ /Gordon Tomlinson //Email / : gtomlinson @ overwatch.textron.com __ //(C)//:/ (+1) 571-265-2612* *(W)//:/ //(+1) 703-437-7651// Self defence is not a function of learning tricks but is a function of how quickly and intensely one can arouse one's instinct for survival - */Master Tambo Tetsura/* ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- Marcin Prus Kierownik Projektu ETC-PZL Aerospace Industries Sp. z o.o. Al. Krakowska 110/114, P.O. Box 22 02-256 Warszawa http://www.ai.com.pl tel: (48-22) 846-54-17 wew. 135 fax (48-22) 846-54-18 e-mail: p...@ai.com.pl NIP 522-01-01-817KRS 010025 Sa;d Rejonowy dla m. st. Warszawy w Warszawie XIII Wydzia? Gospodarczy Krajowego Rejestru Sa;dowego. Wniesiony kapita? zak?adowy Spó?ki wynosi 1 000 000 z?otych. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Erratic intersections with long line segments
Thanks Marcin That's sort of what I was thinking that it had to be rounding, our tiles are localized so YX are relatively small but the Z could be any value range on the earth and seabed, 1million,-1million was over kill for the segment length. Be we will look to go the double route . Thanks again for you reply, Gordon Product Manager 3d __ Gordon Tomlinson Email : gtomlinson @ overwatch.textron.com __ From: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Marcin Prus Sent: Wednesday, April 15, 2009 4:01 AM To: OpenSceneGraph Users Subject: Re: [osg-users] Erratic intersections with long line segments Hi Gordon, we had similar problem here. We were standing exactly at the edge of 2 adjacent triangles in large terrain database and osgUtil::LineSegmentIntersector failed because of internal floating precision. Using doubles instead of floats inside osgUtil::LineSegmentIntersector solved our problems. I've made submission on 18.02.2009 with modified LineSegmentIntersector using cmake flag to set float or double precision internally but it never got into the trunk. You can look at it and create your own LineSegmentIntersectorDbl : public LineSegmentIntersector with double maths inside. Perhaps this will help - it did in our case Best, Marcin Prus Tomlinson, Gordon pisze: HI All I posting this for one of my folks who's is having some erratic results when using a long vertical line segment and the standard osgUtil::LineSegmentIntersector Basically when he sets a line segment up with end X,Y, 100 and start X,Y, -100 , occasionally we fail to get a hit even though we are in the middle of the terrain skin, although moving the X,Y several meters in any direction and we get a hit. If we reduce the Z of the line segment to 500k and -500k this happens less errant fails, if we reduce the Z's to 1k, -1k then we never get a fail, further when we are failing with the intersections if the camera is further away from the intersection the less fails we get, the more we move closer to the intersection point the more fails we get. Our Near and Far clip are fixed, 1 to 10-20k , the terrain skin is stanard OSG geometry, nothing fancy, some lods, but the level and which lod is showing does not seem to be the issue I'm at at a loss to why this may be happening, we are not doing anything out the oridnary in this case that I can think that would cause this erratic behaviour , any one seen anything like this before ? thanks Gordon Product Manager 3d __ Gordon Tomlinson Email : gtomlinson @ overwatch.textron.com __ (C): (+1) 571-265-2612 (W): (+1) 703-437-7651 Self defence is not a function of learning tricks but is a function of how quickly and intensely one can arouse one's instinct for survival - Master Tambo Tetsura ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- Marcin Prus Kierownik Projektu ETC-PZL Aerospace Industries Sp. z o.o. Al. Krakowska 110/114, P.O. Box 22 02-256 Warszawa http://www.ai.com.pl tel: (48-22) 846-54-17 wew. 135 fax (48-22) 846-54-18 e-mail: p...@ai.com.pl NIP 522-01-01-817KRS 010025 Sąd Rejonowy dla m. st. Warszawy w Warszawie XIII Wydział Gospodarczy Krajowego Rejestru Sądowego. Wniesiony kapitał zakładowy Spółki wynosi 1 000 000 złotych. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] Erratic intersections with long line segments
HI All I posting this for one of my folks who's is having some erratic results when using a long vertical line segment and the standard osgUtil::LineSegmentIntersector Basically when he sets a line segment up with end X,Y, 100 and start X,Y, -100 , occasionally we fail to get a hit even though we are in the middle of the terrain skin, although moving the X,Y several meters in any direction and we get a hit. If we reduce the Z of the line segment to 500k and -500k this happens less errant fails, if we reduce the Z's to 1k, -1k then we never get a fail, further when we are failing with the intersections if the camera is further away from the intersection the less fails we get, the more we move closer to the intersection point the more fails we get. Our Near and Far clip are fixed, 1 to 10-20k , the terrain skin is stanard OSG geometry, nothing fancy, some lods, but the level and which lod is showing does not seem to be the issue I'm at at a loss to why this may be happening, we are not doing anything out the oridnary in this case that I can think that would cause this erratic behaviour , any one seen anything like this before ? thanks Gordon Product Manager 3d __ Gordon Tomlinson Email : gtomlinson @ overwatch.textron.com __ (C): (+1) 571-265-2612 (W): (+1) 703-437-7651 Self defence is not a function of learning tricks but is a function of how quickly and intensely one can arouse one's instinct for survival - Master Tambo Tetsura ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
