Planet grids

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chris
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Planet grids

Post #1by chris » 12.03.2008, 19:05

I've implemented planetographic grids for Celestia. They're rendered as lines, not textures, and can be toggled on and off for any planet:
Image

Useful? If so, what else would you like to see from this feature? Any suggestions on the appearance?

--Chris

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Post #2by t00fri » 12.03.2008, 19:20

VERY useful!

F.
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Post #3by ElChristou » 12.03.2008, 20:25

Equator in a different color?
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Post #4by selden » 12.03.2008, 22:06

It'd be nice if the prime meridian had a unique color, too.

And if the colors were settable, as the orbital colors are now.
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Post #5by chris » 12.03.2008, 22:17

selden wrote:It'd be nice if the prime meridian had a unique color, too.

And if the colors were settable, as the orbital colors are now.


What about using a thicker line instead (or in addition to) of a different colored line?

It's easy to make the colors settable; I'll do that.

I think it could also be useful to show a circle depicting the the terminator.

--Chris

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Post #6by selden » 12.03.2008, 22:50

chris wrote:What about using a thicker line instead (or in addition to) of a different colored line?
That sounds reasonable, too. I think it's desirable to be able to quickly locate the origin of the coordinate system.

It's easy to make the colors settable; I'll do that.
Thanks!
I think it could also be useful to show a circle depicting the the terminator.
I agree.
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Post #7by Johaen » 12.03.2008, 23:19

Just an idea, but as you zoom in, the precision (maybe a different word that I can't think of) of the lines increases. So in that picture, it's every 10 degrees, but as you get closer it could be every 8 degrees, then 6, then 4, etc, or something similar. Just an idea. Not sure if it would be useful.
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Post #8by ajtribick » 12.03.2008, 23:23

It might be nice to use the degree symbol, but I'm not sure of the typical conventions here.

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Post #9by Cham » 12.03.2008, 23:26

Ooh, this is VERY nice ! I was asking for something like this before (grids on planets and moons).

I didn't tested it yet, but I agree that the resolution should be made scale dependant (if it isn't already).

Also, we should have a different line rendering (thikness and color) for the equator, and the reference meridian.
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Post #10by chris » 13.03.2008, 01:51

Here's another shot with the equator marked in a different color and line width. Also shown is an arrow indicting the direction to the orbit origin (in this case Saturn):

Image

--Chris

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Post #11by ElChristou » 13.03.2008, 01:58

Will the grid stay active if one go to ground?
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Post #12by Chuft-Captain » 13.03.2008, 02:11

I assume that as you get closer, the lines don't become thicker or blurred ie. they scale automatically (this is good :) )

One thing that might be nice is an option to adjust the boldness/contrast of the lines. ie. for a subtler effect.
One way to achieve this effect might be to allow the transparency of the lines to be specified. Is this possible?

This could be a percentage value between 0-100 where zero is completely opaque (as already shown),
and 100 would be totally transparent, and hence invisible.

This could be in addition to, or in fact instead of the current on/off functionality already provided, because
0% transparency would correspond to ON, and 100% transparency would correspond to OFF.

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Re: Planet grids

Post #13by duds26 » 27.03.2008, 14:03

It would be good to have an option in the viewing options
(Where also visibility with planets, names, orbits, star names, etc)
To be able to toggle it on or off.

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Re: Planet grids

Post #14by volcanopele » 27.03.2008, 17:05

Oh wow, I didn't notice this before. I was just about to create alt textures with grids for the Galileans and Saturn's major moons.

This is very useful!
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Re: Planet grids

Post #15by volcanopele » 11.04.2008, 22:22

Noticed this issue with the grid labels that appear visible even when there is a body between the observer and the world that has the grid on.

RPCROSS3_celestia_grid_3.png
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Re: Planet grids

Post #16by chris » 11.04.2008, 22:25

volcanopele wrote:Noticed this issue with the grid labels that appear visible even when there is a body between the observer and the world that has the grid on.

RPCROSS3_celestia_grid_4.png

I'll have a look at this--I'm pretty sure already that I have a handle on what's going wrong.

--Chris

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Re: Planet grids

Post #17by ElChristou » 12.04.2008, 01:27

Chris, it you are able to define the global color of a body to do the planetshine, I was wondering if it could be possible to use this data to generate the color of the grid; in fact not the color but the value...

What I mean is if you have a color, then you could probably get it's value (it's just a desaturation), then the grid would be this value +n (n to be define for a pleasing result). I think the grid should stay in greyscale, no color (too hard to match a great variety of maps), so let's say the value of the global color of Earth is x, then the grid would be x+2 for example... The point is to always have a nicely adapted color grid on all bodies... Possible?
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Re: Planet grids

Post #18by ElChristou » 13.04.2008, 11:39

ElChristou wrote:Chris, it you are able to define the global color of a body to do the planetshine, I was wondering if it could be possible to use this data to generate the color of the grid; in fact not the color but the value...

What I mean is if you have a color, then you could probably get it's value (it's just a desaturation), then the grid would be this value +n (n to be define for a pleasing result). I think the grid should stay in greyscale, no color (too hard to match a great variety of maps), so let's say the value of the global color of Earth is x, then the grid would be x+2 for example... The point is to always have a nicely adapted color grid on all bodies... Possible?

Chris is the above incomprehensible or I'm just saying again some sort of insanity? :lol:
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Re: Planet grids

Post #19by ElChristou » 20.04.2008, 12:26

ElChristou wrote:Chris is the above incomprehensible or I'm just saying again some sort of insanity? :lol:

Bump... :|
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Re: Planet grids

Post #20by chris » 20.04.2008, 23:57

ElChristou wrote:
ElChristou wrote:Chris is the above incomprehensible or I'm just saying again some sort of insanity? :lol:

Bump... :|

It's not insanity, but it won't work, either. There are two problems: first of all, most planets have the color left at the default value of white (or [ 1 1 1]). But, I don't think that a black grid--which seems to be what would be derived via your method--would look good for most planets.

The second problem is more fundamental: the color specified in the ssc file is intended to be normalized so that the largest component is 1.0. This means that there's no value information present in the color at all. The actual value of the planet disc is derived from albedo, phase, distance to viewer, and distance to the illuminating star.

--Chris


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