Information on the number of sensors that an opensim region can support

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Information on the number of sensors that an opensim region can support

Dr Ramesh Ramloll
Hello there,
Is there some information about any limit on the number of sensors that an opensim region can support by default?
We are planning to use many sensors at one time, some even attached to vehicles and projectiles, are there anything we should be especially careful about regarding their use in this manner?
Thanks
Ramesh
--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: 208-240-0040

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Re: Information on the number of sensors that an opensim region can support

Dahlia Trimble
Sensors are fairly expensive and inefficient as unless you specify a scan with a given key, they must do a linear search of all of the specified entity types in the scene (region). In other words, if you ask for avatars in an area, it must test all avatars in the region, or if you ask for objects it must test all of the objects. These searches also require exclusive access to the region entities, so only one can happen at a time and anything else that needs access must wait (physics, avatar movement, etc.). Therefore adding many sensors doing frequent scans will eventually degrade sim performance and could have a cascading effect. I'm not aware of any numeric limit; it would depend on how many objects and avatars are in the region and how powerful the machine is the sim is running on and how busy it is doing other things. I'd think testing this would be difficult as you may run into a situation where it appears to work fine when you are building/testing but then performs poorly or even fails when there are many avatars in the region. Lacking any known limit but with these concepts in mind, I guess you'll just have to try adding as many as you need and see when something breaks. Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans.

Unfortunately OpenSimulator currently lacks any means of doing efficient spatial queries. This is something I've brought up in development meetings a few times but the idea has never really caught on.

Good luck with your project :)

On Thu, Oct 16, 2014 at 11:21 AM, Dr Ramesh Ramloll <[hidden email]> wrote:
Hello there,
Is there some information about any limit on the number of sensors that an opensim region can support by default?
We are planning to use many sensors at one time, some even attached to vehicles and projectiles, are there anything we should be especially careful about regarding their use in this manner?
Thanks
Ramesh
--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: <a href="tel:208-240-0040" value="+12082400040" target="_blank">208-240-0040

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Re: Information on the number of sensors that an opensim region can support

Dr Ramesh Ramloll
Thanks Dahlia, you provided us with a good tip here ... "Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans."
Thank YOU
Ramesh

On Thu, Oct 16, 2014 at 3:46 PM, Dahlia Trimble <[hidden email]> wrote:
Sensors are fairly expensive and inefficient as unless you specify a scan with a given key, they must do a linear search of all of the specified entity types in the scene (region). In other words, if you ask for avatars in an area, it must test all avatars in the region, or if you ask for objects it must test all of the objects. These searches also require exclusive access to the region entities, so only one can happen at a time and anything else that needs access must wait (physics, avatar movement, etc.). Therefore adding many sensors doing frequent scans will eventually degrade sim performance and could have a cascading effect. I'm not aware of any numeric limit; it would depend on how many objects and avatars are in the region and how powerful the machine is the sim is running on and how busy it is doing other things. I'd think testing this would be difficult as you may run into a situation where it appears to work fine when you are building/testing but then performs poorly or even fails when there are many avatars in the region. Lacking any known limit but with these concepts in mind, I guess you'll just have to try adding as many as you need and see when something breaks. Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans.

Unfortunately OpenSimulator currently lacks any means of doing efficient spatial queries. This is something I've brought up in development meetings a few times but the idea has never really caught on.

Good luck with your project :)

On Thu, Oct 16, 2014 at 11:21 AM, Dr Ramesh Ramloll <[hidden email]> wrote:
Hello there,
Is there some information about any limit on the number of sensors that an opensim region can support by default?
We are planning to use many sensors at one time, some even attached to vehicles and projectiles, are there anything we should be especially careful about regarding their use in this manner?
Thanks
Ramesh
--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: <a href="tel:208-240-0040" value="+12082400040" target="_blank">208-240-0040

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--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: 208-240-0040

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Re: Information on the number of sensors that an opensim region can support

Mic Bowman
Depending on your requirements... you can use llVolumeDetect() & check for collisions. That uses the physics acceleration structures. 

--mic


On Thu, Oct 16, 2014 at 12:49 PM, Dr Ramesh Ramloll <[hidden email]> wrote:
Thanks Dahlia, you provided us with a good tip here ... "Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans."
Thank YOU
Ramesh

On Thu, Oct 16, 2014 at 3:46 PM, Dahlia Trimble <[hidden email]> wrote:
Sensors are fairly expensive and inefficient as unless you specify a scan with a given key, they must do a linear search of all of the specified entity types in the scene (region). In other words, if you ask for avatars in an area, it must test all avatars in the region, or if you ask for objects it must test all of the objects. These searches also require exclusive access to the region entities, so only one can happen at a time and anything else that needs access must wait (physics, avatar movement, etc.). Therefore adding many sensors doing frequent scans will eventually degrade sim performance and could have a cascading effect. I'm not aware of any numeric limit; it would depend on how many objects and avatars are in the region and how powerful the machine is the sim is running on and how busy it is doing other things. I'd think testing this would be difficult as you may run into a situation where it appears to work fine when you are building/testing but then performs poorly or even fails when there are many avatars in the region. Lacking any known limit but with these concepts in mind, I guess you'll just have to try adding as many as you need and see when something breaks. Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans.

Unfortunately OpenSimulator currently lacks any means of doing efficient spatial queries. This is something I've brought up in development meetings a few times but the idea has never really caught on.

Good luck with your project :)

On Thu, Oct 16, 2014 at 11:21 AM, Dr Ramesh Ramloll <[hidden email]> wrote:
Hello there,
Is there some information about any limit on the number of sensors that an opensim region can support by default?
We are planning to use many sensors at one time, some even attached to vehicles and projectiles, are there anything we should be especially careful about regarding their use in this manner?
Thanks
Ramesh
--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: <a href="tel:208-240-0040" value="+12082400040" target="_blank">208-240-0040

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--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: <a href="tel:208-240-0040" value="+12082400040" target="_blank">208-240-0040

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Re: Information on the number of sensors that an opensim region can support

Dr Ramesh Ramloll
Physics unfortunately does not work as well as we hoped regarding collision detection ... so trying to find work arounds. For e.g. if a projectile is moving beyond a certain speed, the physics frame delay may be too large and collsions are missed. So far we seem to have had better results with sensors (only time and further testing will tell)

On Thu, Oct 16, 2014 at 4:06 PM, Mic Bowman <[hidden email]> wrote:
Depending on your requirements... you can use llVolumeDetect() & check for collisions. That uses the physics acceleration structures. 

--mic


On Thu, Oct 16, 2014 at 12:49 PM, Dr Ramesh Ramloll <[hidden email]> wrote:
Thanks Dahlia, you provided us with a good tip here ... "Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans."
Thank YOU
Ramesh

On Thu, Oct 16, 2014 at 3:46 PM, Dahlia Trimble <[hidden email]> wrote:
Sensors are fairly expensive and inefficient as unless you specify a scan with a given key, they must do a linear search of all of the specified entity types in the scene (region). In other words, if you ask for avatars in an area, it must test all avatars in the region, or if you ask for objects it must test all of the objects. These searches also require exclusive access to the region entities, so only one can happen at a time and anything else that needs access must wait (physics, avatar movement, etc.). Therefore adding many sensors doing frequent scans will eventually degrade sim performance and could have a cascading effect. I'm not aware of any numeric limit; it would depend on how many objects and avatars are in the region and how powerful the machine is the sim is running on and how busy it is doing other things. I'd think testing this would be difficult as you may run into a situation where it appears to work fine when you are building/testing but then performs poorly or even fails when there are many avatars in the region. Lacking any known limit but with these concepts in mind, I guess you'll just have to try adding as many as you need and see when something breaks. Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans.

Unfortunately OpenSimulator currently lacks any means of doing efficient spatial queries. This is something I've brought up in development meetings a few times but the idea has never really caught on.

Good luck with your project :)

On Thu, Oct 16, 2014 at 11:21 AM, Dr Ramesh Ramloll <[hidden email]> wrote:
Hello there,
Is there some information about any limit on the number of sensors that an opensim region can support by default?
We are planning to use many sensors at one time, some even attached to vehicles and projectiles, are there anything we should be especially careful about regarding their use in this manner?
Thanks
Ramesh
--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: <a href="tel:208-240-0040" value="+12082400040" target="_blank">208-240-0040

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[hidden email]
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--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: <a href="tel:208-240-0040" value="+12082400040" target="_blank">208-240-0040

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--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: 208-240-0040

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Re: Information on the number of sensors that an opensim region can support

Michael Emory Cerquoni
llVolumeDetect is completely unreliable in Bulletsim currently, i would not try using it to much if your running Bullet.

On Thu, Oct 16, 2014 at 4:13 PM, Dr Ramesh Ramloll <[hidden email]> wrote:
Physics unfortunately does not work as well as we hoped regarding collision detection ... so trying to find work arounds. For e.g. if a projectile is moving beyond a certain speed, the physics frame delay may be too large and collsions are missed. So far we seem to have had better results with sensors (only time and further testing will tell)

On Thu, Oct 16, 2014 at 4:06 PM, Mic Bowman <[hidden email]> wrote:
Depending on your requirements... you can use llVolumeDetect() & check for collisions. That uses the physics acceleration structures. 

--mic


On Thu, Oct 16, 2014 at 12:49 PM, Dr Ramesh Ramloll <[hidden email]> wrote:
Thanks Dahlia, you provided us with a good tip here ... "Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans."
Thank YOU
Ramesh

On Thu, Oct 16, 2014 at 3:46 PM, Dahlia Trimble <[hidden email]> wrote:
Sensors are fairly expensive and inefficient as unless you specify a scan with a given key, they must do a linear search of all of the specified entity types in the scene (region). In other words, if you ask for avatars in an area, it must test all avatars in the region, or if you ask for objects it must test all of the objects. These searches also require exclusive access to the region entities, so only one can happen at a time and anything else that needs access must wait (physics, avatar movement, etc.). Therefore adding many sensors doing frequent scans will eventually degrade sim performance and could have a cascading effect. I'm not aware of any numeric limit; it would depend on how many objects and avatars are in the region and how powerful the machine is the sim is running on and how busy it is doing other things. I'd think testing this would be difficult as you may run into a situation where it appears to work fine when you are building/testing but then performs poorly or even fails when there are many avatars in the region. Lacking any known limit but with these concepts in mind, I guess you'll just have to try adding as many as you need and see when something breaks. Keep in mind that specifying a scan with a key or using llGetObjectDetails with a known key is likely far more efficient than doing arbitrary scans.

Unfortunately OpenSimulator currently lacks any means of doing efficient spatial queries. This is something I've brought up in development meetings a few times but the idea has never really caught on.

Good luck with your project :)

On Thu, Oct 16, 2014 at 11:21 AM, Dr Ramesh Ramloll <[hidden email]> wrote:
Hello there,
Is there some information about any limit on the number of sensors that an opensim region can support by default?
We are planning to use many sensors at one time, some even attached to vehicles and projectiles, are there anything we should be especially careful about regarding their use in this manner?
Thanks
Ramesh
--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: <a href="tel:208-240-0040" value="+12082400040" target="_blank">208-240-0040

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http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-users



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[hidden email]
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--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: <a href="tel:208-240-0040" value="+12082400040" target="_blank">208-240-0040

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[hidden email]
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--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, CEO CTO DeepSemaphore LLC, Affiliate Research Associate Professor, Idaho State University, Pocatello, ID 83209 Tel: 208-240-0040

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[hidden email]
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--
Michael Emory Cerquoni

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