Hello. I have a few newbie questions I need some help with.
I am currently using a mac powerbook G4, with an ATI radion/64mb (I will buy a windoz box later this week to play with the more complete implimentation) and I am running 10.3.4.
1. When I am the moon, or Mars (as example) there is some sort of odd lighting effects as if there is a Stones concert going on. It appears to be some sort of emission/ambient light from multiple sources but I can’t track them down. How do I get rid of these? As a purist I find it annoying. I know it is a simple deal to turn off, I just can’t find the “switch”!
2. Virtual Textures. Is there an implementation for VT’s on Mac? I used the “Dummies” version as a test, but get garbage.
3. Has anyone produced a “local area of detail” (LOD) for the mars surface? I am thinking MER rovers here. Panorams may be the easiest implementation since the folks at JPL have provided such cool content.
4. Has anyone worked on Rayleigh scattering of light when close to the surface of a planet? This is particularly important with Earth and Mars.
5. Square Inverse law. Has this been looked at by anyone? For the sake of clarity, this is the intensity of light observed from a source of constant intrinsic luminosity falls off as the square of the distance from the object. This is known as the inverse square law for light intensity. This will be particularly interesting when applied to the “flair” texture. I can’t tell, it may be already implemented.
6. Has anyone implemented “all sky” views matched to the stars.dat? In a previous and similer sim project I worked on we placed these all sky’s out just past the far clipping plane (SGI Performer API on LINUX) and using a target star in the data base tried, with reasonable success, to align the image and the data. We used a cube with the texture inside the cube. The coolest bit was using Axel Mellinger’s superb optical all sky of the milkyway. Once we parsed out the cacophony of stars in the optical image to be left with just the H2 regions, dust, Galactic core etc., when overlayed with the star data it was quite realistic (if you had HUGE eyes) and very stunning.
That being said, has this been done? A slider, to scroll between different wavelengths from a starting point of the optical Mellinger image, would be way more than cool. I’m afraid this will be beyond my programming skills.
OK, enough for now! But I’ll have much more….
Howard
Newbie ?'s Lights, VT's on Mac, All Skys and a few others
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Guest
Hello Howard,
To run through you questions.
1. Press ctrl V to cycle the rendering path.
2.VT's work on the mac but they are very finnicky on all systems. You have to make sure everythig is est up just so. I would suggest the BLue Marble DDS by Walton Comer. It's availabe at the Earth Section of my site. It is defined as an alternate surface so ctrl-click on the earth when you have it installed, and select Alternate Texture to turn it on. If the earth changes color, it worked.
3. No area of detail VT's for martian surface, but see my site for the best whole surface textures and models of martian rovers etc. (Under spacecraft)
4.Rayleigh scattering is just when photons bounce of atoms elastically, most noticable when on reflective mdeia like ice and water. So I think you are referring to specmaps? See my site for these.
5 Square inverse law. See the FAQ at the top of this forum for info about lighting in Celestia. If this doens't answer your question, ask again.
6. This sounds really good and many people could implement this, if given the source data. Do you have a link?
As a side note, you mention things that "would be way more than cool. I’m afraid this will be beyond my programming skills." We have quite an abundance of poeple that are very good at thinking of things that are way more than cool but beyond their programming skills. We have a dearth of people that implement things. So I am not trying to be a wet blanket but suggesting difficult but nice features and being an "idea generator" doesn't really help the program along. That said we always like to know cool ideas and maybe you will get soeone excited about you project. Also, I and many others hung aroudn suggesting this and that and it was only months laters, I realized hwo I coudl make a concrete contribution. (my under construction site) If you have any other questions, please don't hesitate to ask.
Cheers, Joe
To run through you questions.
1. Press ctrl V to cycle the rendering path.
2.VT's work on the mac but they are very finnicky on all systems. You have to make sure everythig is est up just so. I would suggest the BLue Marble DDS by Walton Comer. It's availabe at the Earth Section of my site. It is defined as an alternate surface so ctrl-click on the earth when you have it installed, and select Alternate Texture to turn it on. If the earth changes color, it worked.
3. No area of detail VT's for martian surface, but see my site for the best whole surface textures and models of martian rovers etc. (Under spacecraft)
4.Rayleigh scattering is just when photons bounce of atoms elastically, most noticable when on reflective mdeia like ice and water. So I think you are referring to specmaps? See my site for these.
5 Square inverse law. See the FAQ at the top of this forum for info about lighting in Celestia. If this doens't answer your question, ask again.
6. This sounds really good and many people could implement this, if given the source data. Do you have a link?
As a side note, you mention things that "would be way more than cool. I’m afraid this will be beyond my programming skills." We have quite an abundance of poeple that are very good at thinking of things that are way more than cool but beyond their programming skills. We have a dearth of people that implement things. So I am not trying to be a wet blanket but suggesting difficult but nice features and being an "idea generator" doesn't really help the program along. That said we always like to know cool ideas and maybe you will get soeone excited about you project. Also, I and many others hung aroudn suggesting this and that and it was only months laters, I realized hwo I coudl make a concrete contribution. (my under construction site) If you have any other questions, please don't hesitate to ask.
Cheers, Joe
Unfortunately, Axel's all-sky maps are copyrighted and may not be redistributed for use with Celestia without his permission. I asked about it, but he never responded.
Some low resolution IR all-sky maps are available, projected onto the interior surface of a sphere. See http://www.lns.cornell.edu/~seb/celestia/billboard.html#7.2 and http://www.lns.cornell.edu/~seb/celestia/catalogs.htm#3.5.9
Some low resolution IR all-sky maps are available, projected onto the interior surface of a sphere. See http://www.lns.cornell.edu/~seb/celestia/billboard.html#7.2 and http://www.lns.cornell.edu/~seb/celestia/catalogs.htm#3.5.9
Selden
Selden-
Here's a condensed version of me trying to have a conversation with every newbie that comes along.
Newbie: Wouldn't it be great if Celestia was actually a a photrealistc simulation of even the unkown universe presented in all readiation wavelengths with animation and realistic explosions and volcanoes and aliens and Celestia would aslo wash your car and check you mail while you were away?
Me: Those things are actually kind of hard to do for the following reasons...
Selden: (interjecting) Actually I have already implemented crude car-washing functionality. Please see a section of my mazelike website you hadn't previosuly been aware of for a car-washing plugin, instructions how to create other chore-doing plugins easily and example pictures of Celestia washing yor car. A couple of months ago, I had attempted to do exaclty what you requested, but it turns out to be impossible because of limitng external constraints etc etc.
Seriously Selden, I don't think I have even seen half of what you have on your site. Are you ever going to condense it down? Just the things you have created are larger than my entire catalog! What are the highlights of what you're got? Anyway, back to work.
Joe
Here's a condensed version of me trying to have a conversation with every newbie that comes along.
Newbie: Wouldn't it be great if Celestia was actually a a photrealistc simulation of even the unkown universe presented in all readiation wavelengths with animation and realistic explosions and volcanoes and aliens and Celestia would aslo wash your car and check you mail while you were away?
Me: Those things are actually kind of hard to do for the following reasons...
Selden: (interjecting) Actually I have already implemented crude car-washing functionality. Please see a section of my mazelike website you hadn't previosuly been aware of for a car-washing plugin, instructions how to create other chore-doing plugins easily and example pictures of Celestia washing yor car. A couple of months ago, I had attempted to do exaclty what you requested, but it turns out to be impossible because of limitng external constraints etc etc.
Seriously Selden, I don't think I have even seen half of what you have on your site. Are you ever going to condense it down? Just the things you have created are larger than my entire catalog! What are the highlights of what you're got? Anyway, back to work.
Joe
alphap1us...I think a bit of respect is due here...Selden has a great resource which he's compiled for us...for free!...get real people! Help us to help you.
Howard....your questions are very real and it looks to me you're halfway to an answer on these...I think you may be a developer!....It's all greek to me I'm afraid.
Very interesting thread btw.
Regards...bh.
Howard....your questions are very real and it looks to me you're halfway to an answer on these...I think you may be a developer!....It's all greek to me I'm afraid.
Very interesting thread btw.
Regards...bh.
Hi All,
Please let me clarify that I meant absolutley no disrespect to Selden. He has done amazing work in Celestia and I love hs site. He has done so much that I can't even comprehend it all at once hence the subject of my little joke. Yeah, it did sound a little mean there at the end but I meant it all in complete silliness. I am in the midst of a hellish finals week right now so my sense of social norms is a little off... Anyway three cheers for Selden, and I am really excited about Howard's ideas. I hope they are realized in Celestia!
Cheers,
Joe
Please let me clarify that I meant absolutley no disrespect to Selden. He has done amazing work in Celestia and I love hs site. He has done so much that I can't even comprehend it all at once hence the subject of my little joke. Yeah, it did sound a little mean there at the end but I meant it all in complete silliness. I am in the midst of a hellish finals week right now so my sense of social norms is a little off... Anyway three cheers for Selden, and I am really excited about Howard's ideas. I hope they are realized in Celestia!
Cheers,
Joe
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Topic authorhoward
- Posts: 18
- Joined: 04.06.2004
- With us: 20 years 5 months
- Location: Colorado Springs/Denver
Hello all.
Re: Rayleigh scattering is (named after after Lord Rayleigh) is the scattering of light by particles smaller than the wavelength of the light. It occurs when light travels in transparent solids and liquids, but is most prominently seen in gases. Rayleigh scattering of sunlight from particles in the atmosphere is the reason why the light from the sky is blue on Earth. A notable exception occurs during sunrise and sunset, when the Sun's light must pass through a much greater thickness of the atmosphere to reach an observer on the ground. This extra distance causes multiple scatterings of blue light, but relatively little scattering of red light; this is seen as a pronounced red-hued sky in the direction towards the sun.
In the case of Mars, the sky actually has a blue coloring but the intensity of fine particle of dust, finer than that of flour, causes the atmosphere to take on a more butterscotch appearance. Pathfinder and Opportunity have both recorded blue sky, usually around sunset and when it has been particularly clear. Interestingly the dust is not likely introduced into the atmosphere by wind but by 10’s of km high dust devils. We have photographed these from orbit!
I will play with the vt’s further till I get them to work.!
I tried the render cycle with no luck. I’ll keep poking.
I for one have been making real use of Selden’s site, in fact I studied his bits on panorams this afternoon. He has organized some quite useful information. Granted there is a lot…
The bit on the panorams was working for me for both the LOD at the surface and the All Sky implementation. One could model a HR mars surface (in fact you could use the 3d models created from the MER imaging) in Maya lets say, shoot a panoram and load it in as suggested on Selden’s site. Problem is smoothly getting to it, i.g. flying up to that position without a harsh transition. Worth some thought anyway.
Wait till you here my ideas for using the MOLA data as a “Virtual Geometry Map” VGM! Works well for loading quite refined 1/128th degrees “meshes” as you all call them, with VT’s, at high frame rates. Got the methods, ain’t got the smarts…
As for the all skys, we were, with the Cosmic Atlas, implementing a similar panoramic technique albeit the texture was just outside of the far clipping plane and thus you were never able to “approach” it. Just building a large sphere or box and mapping to the inside would not cut it as you would now be able to experience “the edge of the universe” which is not possible. I am not sure how Celestia manages clip mapping or clipping planes so I can not answer if it can be done. Again, a programmer I am not.
I can probably get Axel’s work if someone wants to take a swing at this. I have permission from him to use it in educational, not for sale products. I think this sim qualifies but I will check with him. I also can maybe get my hands on the “de stared” version which would be better and may not have copyright restrictions. I will look into it.
Another question. Anyone know of some better textures for Jacks Cassini_v2 model. Selden, any luck on the new TLE for Cassini? I may be able to help there as well. One of my clients is LMC. I’m also interested to find out if anyone has mapped .mov files to a single polygon. Idea here is to do say an engine burn as a QTVR and map it to a polygon with the normal always facing you. A dynamic billboard kinda deal…
Re: Rayleigh scattering is (named after after Lord Rayleigh) is the scattering of light by particles smaller than the wavelength of the light. It occurs when light travels in transparent solids and liquids, but is most prominently seen in gases. Rayleigh scattering of sunlight from particles in the atmosphere is the reason why the light from the sky is blue on Earth. A notable exception occurs during sunrise and sunset, when the Sun's light must pass through a much greater thickness of the atmosphere to reach an observer on the ground. This extra distance causes multiple scatterings of blue light, but relatively little scattering of red light; this is seen as a pronounced red-hued sky in the direction towards the sun.
In the case of Mars, the sky actually has a blue coloring but the intensity of fine particle of dust, finer than that of flour, causes the atmosphere to take on a more butterscotch appearance. Pathfinder and Opportunity have both recorded blue sky, usually around sunset and when it has been particularly clear. Interestingly the dust is not likely introduced into the atmosphere by wind but by 10’s of km high dust devils. We have photographed these from orbit!
I will play with the vt’s further till I get them to work.!
I tried the render cycle with no luck. I’ll keep poking.
I for one have been making real use of Selden’s site, in fact I studied his bits on panorams this afternoon. He has organized some quite useful information. Granted there is a lot…
The bit on the panorams was working for me for both the LOD at the surface and the All Sky implementation. One could model a HR mars surface (in fact you could use the 3d models created from the MER imaging) in Maya lets say, shoot a panoram and load it in as suggested on Selden’s site. Problem is smoothly getting to it, i.g. flying up to that position without a harsh transition. Worth some thought anyway.
Wait till you here my ideas for using the MOLA data as a “Virtual Geometry Map” VGM! Works well for loading quite refined 1/128th degrees “meshes” as you all call them, with VT’s, at high frame rates. Got the methods, ain’t got the smarts…
As for the all skys, we were, with the Cosmic Atlas, implementing a similar panoramic technique albeit the texture was just outside of the far clipping plane and thus you were never able to “approach” it. Just building a large sphere or box and mapping to the inside would not cut it as you would now be able to experience “the edge of the universe” which is not possible. I am not sure how Celestia manages clip mapping or clipping planes so I can not answer if it can be done. Again, a programmer I am not.
I can probably get Axel’s work if someone wants to take a swing at this. I have permission from him to use it in educational, not for sale products. I think this sim qualifies but I will check with him. I also can maybe get my hands on the “de stared” version which would be better and may not have copyright restrictions. I will look into it.
Another question. Anyone know of some better textures for Jacks Cassini_v2 model. Selden, any luck on the new TLE for Cassini? I may be able to help there as well. One of my clients is LMC. I’m also interested to find out if anyone has mapped .mov files to a single polygon. Idea here is to do say an engine burn as a QTVR and map it to a polygon with the normal always facing you. A dynamic billboard kinda deal…
Howard,
The most recent prerelease for Windows (v1.3.2pre8 or later) includes an up-to-date xyz trajectory for Cassini, generated by Grant Hutchison. It can be downloaded from SourceForge for use with older versions of Celestia. I'll add a comment to my "spacecraft" page about that.
Celestia doesn't seem to have the "clipping boundary" effect that you describe, at least not for externally defined objects. If you can see it, you can goto it. Unfortunately, the way distances are currently implemented, it's possible to define very large objects (radius > 1e6 LY? 1e19 for sure) that are visible on some recent models of NVidia graphics cards but not visible at all on some recent ATI cards.
I agree that my Web site, especially the Addons I've created, could be better organized. I keep finding more entertaining things to do, though
The most recent prerelease for Windows (v1.3.2pre8 or later) includes an up-to-date xyz trajectory for Cassini, generated by Grant Hutchison. It can be downloaded from SourceForge for use with older versions of Celestia. I'll add a comment to my "spacecraft" page about that.
Celestia doesn't seem to have the "clipping boundary" effect that you describe, at least not for externally defined objects. If you can see it, you can goto it. Unfortunately, the way distances are currently implemented, it's possible to define very large objects (radius > 1e6 LY? 1e19 for sure) that are visible on some recent models of NVidia graphics cards but not visible at all on some recent ATI cards.
I agree that my Web site, especially the Addons I've created, could be better organized. I keep finding more entertaining things to do, though
Selden
Howard,
Jack's model is the best we have.
It's included in the latest Celestia prerelease and can be downloaded from SourceForge.
Don't forget that surface textures are just pictures. I suspect Jack would be willing to accept replacements if better ones were to be made available to him...
I know of no plans to make Celestia directly display realtime telemetry.
Don't forget, though, that an InfoURL can be associated with any object that will invoke your browser and open the specified Web page.
My understanding is that the person who does the MacOS ports always waits until the final release is available. He doesn't port any of the prereleases.
Apparently there's a PC emulator available that runs under MacOS, for what that's worth.
Jack's model is the best we have.
It's included in the latest Celestia prerelease and can be downloaded from SourceForge.
Don't forget that surface textures are just pictures. I suspect Jack would be willing to accept replacements if better ones were to be made available to him...
I know of no plans to make Celestia directly display realtime telemetry.
Don't forget, though, that an InfoURL can be associated with any object that will invoke your browser and open the specified Web page.
My understanding is that the person who does the MacOS ports always waits until the final release is available. He doesn't port any of the prereleases.
Apparently there's a PC emulator available that runs under MacOS, for what that's worth.
Selden
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julesstoop
- Posts: 408
- Joined: 27.03.2002
- With us: 22 years 8 months
- Location: Leiden, The Netherlands
VirtualPC - the emulator you are probably refering to - unfortunately doesn't natively make use of any graphics hardware: your video-board is emulated in software as well. All the GPU tasks have to be done via a simulated CPU, so it's extremely slow to do any real-time 3D rendering in VPC. The yet to be released new version (7), the first full version by Microsoft (who bought the package from Connectix about a year ago) is supposed to bring some native support for video hardware, though I'd rather keep using the native (Mac OS) version.
Lapinism matters!
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