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Thread: Sunsky Issue

  1. #1
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    Sunsky Issue

    Hello all:

    I am working on an image and I have I problem that I can't figure out. May be you know.

    Please see the attached images.

    There is only one light in the scene, a SK Sun Light acting as the sun (I've called the light new sun). I've set it up as manual, so I can move the light to different positions and the light colour changes accordingly. So far so good.

    I am trying to recreate an early morning scene, with a very low sun. I've added a Textured Environment with the Sunsky procedural, so that the sun is visible in the sky and there is some sort of halo around it.

    The issue is that the position of the SK Sun Light doesn't match the position of the sun disk that shows up in the sky. However, they are linked, If I move the light the disk moves accordingly. You can see in the test render that the shadow of the bowl on the table doesn't match the position of the sun disk in the sky. In one of the images attached, the orange dotted line shows the location of the light in regard to the house and the camera.

    How do I sort this out?. I've looked in the options for both the textured environment and the light, but I am clueless.

    As a side note, you may wonder why the balustrade is not casting shadows on the floors, as it happens my nodal set up for the floor texture is causing the shadows not to show up, I am working this.

    The hills are actual (simple) geometry stretching 2km from the house, so the house is tiny when compared with the terrain model. I've got low poly trees all over the hills, but they are switched off of this test render as they significantly increase my render times. Fog is on and causes the nice shift in colour from green to grey in the faraway hills.

    Any tips on how to improve the "environment" to create a morning sky effect would be appreciated. I'd like so render the clouds, but I am pushing my laptop to the limit and for what I've seen in the forums creating good clouds is quite a subject in itself and I just need to finish this quickly, so I'll probably add some clouds in post. I am using LW 2015

    Regards

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    Last edited by luzlight; 09-01-2018 at 01:00 PM.

  2. #2
    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by luzlight View Post
    Hello all:

    I am working on an image and I have I problem that I can't figure out. May be you know.

    Please see the attached images.

    There is only one light in the scene, a SK Sun Light acting as the sun (I've called the light new sun). I've set it up as manual, so I can move the light to different positions and the light colour changes accordingly. So far so good.

    I am trying to recreate an early morning scene, with a very low sun. I've added a Textured Environment with the Sunsky procedural, so that the sun is visible in the sky and there is some sort of halo around it.

    The issue is that the position of the SK Sun Light doesn't match the position of the sun disk that shows up in the sky. However, they are linked, If I move the light the disk moves accordingly. You can see in the test render that the shadow of the bowl on the table doesn't match the position of the sun disk in the sky. In one of the images attached, the orange dotted line shows the location of the light in regard to the house and the camera.

    How do I sort this out?. I've looked in the options for both the textured environment and the light, but I am clueless.

    As a side note, you may wonder why the balustrade is not casting shadows on the floors, as it happens my nodal set up for the floor texture is causing the shadows not to show up, I am working this.

    The hills are actual (simple) geometry stretching 2km from the house, so the house is tiny when compared with the terrain model. I've got low poly trees all over the hills, but they are switched off of this test render as they significantly increase my render times. Fog is on and causes the nice shift in colour from green to grey in the faraway hills.

    Any tips on how to improve the "environment" to create a morning sky effect would be appreciated. I'd like so render the clouds, but I am pushing my laptop to the limit and for what I've seen in the forums creating good clouds is quite a subject in itself and I just need to finish this quickly, so I'll probably add some clouds in post. I am using LW 2015

    Regards

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    You are approaching it a bit wrong, you have added textured environment then trying to add sunsky within a procedural, that will not match your light and the sundisc.
    Skip that and add sunsky environment directly in backdrop, not textured environment.

    If you want the halo, you may use the sunsky atmosphere located in the volumetric tab.

  3. #3
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    Thanks Prometheus

    I've removed the Textured Environment and added the Sunsky Environment on the backdrop tab as suggested.


    The problem still there. In the attached image the sun is visible but the dotted line points to the position of the light.

    When you mention the Sunsky Atmosphere on the volumetric tab, do you mean adding it in addition to the Sunsky Environment (in the backdrop) or Instead of Sunsky Environment?.

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  4. #4
    Electron wrangler jwiede's Avatar
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    If you look under volumetrics, you'll see a Sunsky option there as well. Add and enable that (adjusting settings as needed) and you'll get a proper environmental atmospheric hazing effect.
    John W.
    LW2015.3UB/2018.0.7 on MacPro(12C/24T/10.13.6),32GB RAM, NV 980ti

  5. #5
    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by luzlight View Post
    Thanks Prometheus

    I've removed the Textured Environment and added the Sunsky Environment on the backdrop tab as suggested.


    The problem still there. In the attached image the sun is visible but the dotted line points to the position of the light.

    When you mention the Sunsky Atmosphere on the volumetric tab, do you mean adding it in addition to the Sunsky Environment (in the backdrop) or Instead of Sunsky Environment?.

    Click image for larger version. 

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    addition to the sunsky environment, keep the backdrop sunsky and then add the sunsky atmosphere
    additionally, you may also want to hit "m" for the motion tab when you have your sunlight selected, add the sunsky sunmotion plugin, this will make sure your lensflare is following the sun properly if you want a lensflare which you activate on the lights lensflare options,It can be tricky to get the sun lensflare to fade of at horizon and change color etc though.

    The sun also needs to change color when going down, you add that by going to the sunlights lightcolor envelope and add the sunsky suncolor modifier..you have to do this manually for each rgb channel, in the newer 2018 it seems you only have to apply it once and it works, but unfortunately it can not use dp lights and other things are broken there.

    Not sure which lightwave version you use, if it is 2018 that could be a problem.
    Also there is a script call add sunsky, that may work to sett the sun up more correctly..check bottom of his page..

    http://dpont.pagesperso-orange.fr/plugins/Sunsky.html
    or direct..
    http://dpont.pagesperso-orange.fr/pl...Add_Sunsky.zip

    but both mac and lightwave 2018 may be a possible cause of errors.

    After fiddling with both blenders and houdini´s similar type of sky environment (excluding the broken sunsky in 2018) I find that Lightwave´s in fact is the better one of them, apart from that it isn´t
    native and thus may suffer from update continuity..as proven.

    it however doesn´t compete with daz3d´sky environment which is far better than lightwave, houdini, or blender...then you got the full spectral volumetrics sky such as terragen and vue, which is of course the more realistic ones, with longer rendertimes being volumetric and such.

  6. #6
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    Quote Originally Posted by prometheus View Post
    addition to the sunsky environment, keep the backdrop sunsky and then add the sunsky atmosphere
    additionally, you may also want to hit "m" for the motion tab when you have your sunlight selected, add the sunsky sunmotion plugin, this will make sure your lensflare is following the sun properly if you want a lensflare which you activate on the lights lensflare options,It can be tricky to get the sun lensflare to fade of at horizon and change color etc though.

    The sun also needs to change color when going down, you add that by going to the sunlights lightcolor envelope and add the sunsky suncolor modifier..you have to do this manually for each rgb channel, in the newer 2018 it seems you only have to apply it once and it works, but unfortunately it can not use dp lights and other things are broken there.

    Not sure which lightwave version you use, if it is 2018 that could be a problem.
    Also there is a script call add sunsky, that may work to sett the sun up more correctly..check bottom of his page..

    http://dpont.pagesperso-orange.fr/plugins/Sunsky.html
    or direct..
    http://dpont.pagesperso-orange.fr/pl...Add_Sunsky.zip

    but both mac and lightwave 2018 may be a possible cause of errors.

    After fiddling with both blenders and houdini´s similar type of sky environment (excluding the broken sunsky in 2018) I find that Lightwave´s in fact is the better one of them, apart from that it isn´t
    native and thus may suffer from update continuity..as proven.

    it however doesn´t compete with daz3d´sky environment which is far better than lightwave, houdini, or blender...then you got the full spectral volumetrics sky such as terragen and vue, which is of course the more realistic ones, with longer rendertimes being volumetric and such.

    Thanks, I need to check all that !

    I've done some tests placing a fresh SKsunlight and Sunsky Environment. There seems to be an issue.

    Upon placing the new light and setting it immediately to manual, the light is placed automatically at 0 degrees azimuth (which makes the light to sit right on the Z+ axis when seen on top view (lets call that south), and 0 degrees altitude (the light sits on the horizontal plane).

    At this point, the SKsunlight and the sun disk from the Sunsky Environment line up nicely in the views. If the light is then rotated on the horizontal plane (azimuth) with a positive angle (clockwise on top view) up to 179.99 degrees they remain aligned. Beyond that angle the sun disk jumps out of sync. This is shown in the attached images. The vertical angle (altitude) is not an issue, in the attached example I've set that to 9 degrees to make the sun disk visible above the horizon.

    This is what is causing the issue in my original scene. My sun location is way beyond 180 degrees.

    I don't know if this is a bug (I am on a mac, LW 2015.3). Or if this is by design and I a not using the plug in correctly. I'll have to check the other things you've suggested to see if that works.

    Otherwise I'll have to rotate all the models/layers in the scene + all cameras together 180 degrees (how do I do that without loosing their relative positions ???) so they face the other way around so I can place the SKsunlight to shine where I want without triggering the issue.

    I tried also placing a second SKsunlight and switching it off using it only to drive position of the sun disk and make it match the position of the SKsulight actually illuminating the scene. If that make sense. IT sort of works but its a messy workaround.

    I'll try the script you suggested next to see if it improves things.

    Thanks for your help

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    ps: there are multiple typos on the attached images, apologies, it was done in a rush !. I mean sync where I typed sink !
    Last edited by luzlight; 09-03-2018 at 04:22 PM.

  7. #7
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    Quote Originally Posted by jwiede View Post
    If you look under volumetrics, you'll see a Sunsky option there as well. Add and enable that (adjusting settings as needed) and you'll get a proper environmental atmospheric hazing effect.
    Thanks John

    I did a quick test and for I can see the volumetric sun sky option doesn't affect how the sky looks but how the objects are lit. Presumably it affects the light coming from the sky/sun shinning on the objects ???. Is this correct?.

    It's difficult at first to grasp what all the different parts of the plug in do. Not to mention the multiple parameters on each !.

    I'll keep playing with it and do more tests.

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    Quote Originally Posted by prometheus View Post
    The sun also needs to change color when going down, you add that by going to the sunlights lightcolor envelope and add the sunsky suncolor modifier..you have to do this manually for each rgb channel, in the newer 2018 it seems you only have to apply it once and it works, but unfortunately it can not use dp lights and other things are broken there.
    Starting to test your other suggestions.

    I just noticed that the colour of the light changes just by changing the SKsunlight angle (altitude) even without the sun colour modifier. (see attached).

    In the light tab there are two places where to change the colour of the light, the one at the bottom (curiously not labeled) which changes automatically by changing the angle.

    The other place is the one labeled "light colour" just below the light type which doesn't change unless you apply the suncolor modifier. The curious thing is that once the modifier is on, both colour pickers update automatically when changing the light angle, both show the same rgb values but the actual colours shown in the little squares beside the rgb values are not the same !.

    Why would that be??

    Anyway, I keep trying to decipher this...

  9. #9
    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by luzlight View Post
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    Starting to test your other suggestions.

    I just noticed that the colour of the light changes just by changing the SKsunlight angle (altitude) even without the sun colour modifier. (see attached).

    In the light tab there are two places where to change the colour of the light, the one at the bottom (curiously not labeled) which changes automatically by changing the angle.

    The other place is the one labeled "light colour" just below the light type which doesn't change unless you apply the suncolor modifier. The curious thing is that once the modifier is on, both colour pickers update automatically when changing the light angle, both show the same rgb values but the actual colours shown in the little squares beside the rgb values are not the same !.

    Why would that be??

    Anyway, I keep trying to decipher this...
    Will have to ceck and get back to this, what I do know though..I do not think the sk_sunlight is tinting other stuff in the scene with proper ligh color change ..Unless you add that sk_suncolor modifier.
    Working 8 hours so I won´t be back home for a while in order to check it out.

  10. #10
    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by luzlight View Post
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    Starting to test your other suggestions.

    I just noticed that the colour of the light changes just by changing the SKsunlight angle (altitude) even without the sun colour modifier. (see attached).

    In the light tab there are two places where to change the colour of the light, the one at the bottom (curiously not labeled) which changes automatically by changing the angle.

    The other place is the one labeled "light colour" just below the light type which doesn't change unless you apply the suncolor modifier. The curious thing is that once the modifier is on, both colour pickers update automatically when changing the light angle, both show the same rgb values but the actual colours shown in the little squares beside the rgb values are not the same !.

    Why would that be??

    Anyway, I keep trying to decipher this...
    checking back, boy...I guess I haven´t been using lightwave that much currently..have been working with blender more currently, but...I beg you pardon if I have mislead you here...the advice of using sk_suncolor modifier on the light color envelope channel, that is only valid if you use standard lights, like distant light, or dome light...Not if you use the sk_sunlight, it should be automaticly set up I think for the color.
    So don´t mess with the Light color channel if you use the sk_sunlight type, if you use additional dome lights, that option could be useful though.

    And if you in the lights properties set the sk_sunlight postion to manual , you can rotate your light manually with the standard rotate tools, otherwise you need to use the time zone which is harder to control, when you rotate your sk_sunlight..the color should change if you pull down the pitch, but you will not see the color values in that tab change, not until you click on those rgb values..then the values will update.

    I hope all that makes sense now? use the light color with envelope and add suncolor modifier on any standard light, and if you only use the sk_sunlight, you do not have to worry about the values not seemingly changing in that sk_sunlight color tab without an envelope, it is working as it should.

  11. #11
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    Quote Originally Posted by prometheus View Post
    checking back, boy...I guess I haven´t been using lightwave that much currently..have been working with blender more currently, but...I beg you pardon if I have mislead you here...the advice of using sk_suncolor modifier on the light color envelope channel, that is only valid if you use standard lights, like distant light, or dome light...Not if you use the sk_sunlight, it should be automaticly set up I think for the color.
    So don´t mess with the Light color channel if you use the sk_sunlight type, if you use additional dome lights, that option could be useful though.

    And if you in the lights properties set the sk_sunlight postion to manual , you can rotate your light manually with the standard rotate tools, otherwise you need to use the time zone which is harder to control, when you rotate your sk_sunlight..the color should change if you pull down the pitch, but you will not see the color values in that tab change, not until you click on those rgb values..then the values will update.

    I hope all that makes sense now? use the light color with envelope and add suncolor modifier on any standard light, and if you only use the sk_sunlight, you do not have to worry about the values not seemingly changing in that sk_sunlight color tab without an envelope, it is working as it should.

    Hi

    Thanks for taking the time to check.

    Now clear on the suncolor modifier.

    Rotating the SKsunlight either manually by rotating the light icon with the pointer or via the standard rotation tool causes the problem described on my previous posts.

    So I've set the SKsunlight to Time Zone. Choosing a preset for a city on the northern hemisphere will make the sun to describe an arch (sun path) below the X axis (south) when seen in top view from right (east)(morning) to left (west) (afternoon). That is precisely what I needed so I chose Copenhagen in winter (january) in the morning, and that's it, the sun shows up where I wanted. The opposite is true if what one wants is the sun to shine on the opposite side (north) so choosing a city on the southern hemisphere does the trick. Better to use a city well south or well north rather that one near the Ecuator. In the tropic, for a given location, the sunpath flips from north to south depending on the time of the year. (you problaby already know this, but the info may be useful for others). Still, there might be cases - as you pointed out - that it may be tricky to have the sun in exactly the spot when one wants.


    The good thing about setting it to time zone is that everything works as expected. The sun disk from the Sunsky Environment aligns with the SKsunlight so the problem that originated this thread no longer happens.

    Using the Sunsky SunMotion for the lens flare works really nicely. That was a great tip, thanks !

    The SunSky Atmosphere is a tricky one. The render times increase astronomically. From 22min without it(right on the attached image) to 16 hours with it !!! (on the left).

    Because the sun is very low and the light very orangy SunSky atmosphere tints everything with an orange/yellow tone which is probably correct to some extent (and very nice on the mountains) but not what I want to see in the house and the furniture in this particular case, or at least not with such intensity. Other than the change of colour is difficult for me to see what else it is supposed to do. No effect is noticeable in the sky, which is confusing as well. So for this image I am going to have to drop SK Atmosphere.

    Still a few tweaks to do before rendering a final image.

    Thanks again.
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