[Becco_UK]

.

At 9.00 am, Mid Summer, facing sun, the United Kingdom sky doesn't look anything like this.

What's really needed, is the option to choose from several sky types.

I personally like the pink version - always thought the 1.1 sky was plain and drab.

[Thomas An.]

What happens if you reduce the turbidity to 2 ?

[Tyrone Marshall]

I still do not see the problem. Please see my real scale scene below.

I have a main terrain (very large at 4,950ft width [x], 825ft high [y], 4,950ft long [z] and two secondary terrains in the background to complete the scene.

I have a large properly scaled tower at 1,000 ft tall (This is a pretty tall tower by the way).

Camera Station:
63 ft [Y] -

Physical sky location:
San Francisco, CA, USA @ 1PM on May 5th, 2007.
Long: -122.383
Lat: 37.617
GMT: -8.000
San Francisco is 52 feet above sea level.

Atmosphere settings:
3.500 turb
0.328 ozone
1.730 water

ref: http://en.wikipedia.org/wiki/San_Francisco

I have a level camera stationed at an elevation of 63 ft above a [y] height of 0. In my example, 0' ft [y] is equal to sea level.

From this real physical model using a real physical and unbiased render engine I get this result:

Its what I would expect on nice clear blue sky May day in 2007 in the bay area. Of course, that is on one of the days there is not fog in bay area.

I did not use shift lens because I wanted you to see 3 point perspective due to the immense height of the building.



Until there is this much research in the scene, you cannot start talking about there is too much pink in the sky.

I would recommend checking camera settings in reference to shutter speed and fstop and make sure these are set appropriate for an outdoor scene in bright sun light.

[Tyrone Marshall]

.

At 9.00 am, Mid Summer, facing sun, the United Kingdom sky doesn't look anything like this.

What's really needed, is the option to choose from several sky types.

I personally like the pink version - always thought the 1.1 sky was plain and drab.

Where is this plane geographically, is it in the right place? Is it in the right place with respect to elevation? Are your camera settings correct?

More information is needed here?

[Maxer]

I'll e-mail you my file if you wish, just provide me an e-mail address although you don't need it just change you physical sky settings to those that I provided and you will see the result. You might also consider that not all locations are displaying the same way, we know from the tests that Russia and Houston aren't working properly. I have also tried adjusting S-speed and ISO and they have no affect on the pink color of the sky.

[Becco_UK]

Thomas An.: Lowering the turbidity value as you suggested reduces the pink effect. Thanks.

[Tyrone Marshall]

I'll e-mail you my file if you wish, just provide me an e-mail address although you don't need it just change you physical sky settings to those that I provided and you will see the result. You might also consider that not all locations are displaying the same way, we know from the tests that Russia and Houston aren't working properly. I have also tried adjusting S-speed and ISO and they have no affect on the pink color of the sky.

No need to send the file, I could do the exact thing I did with San Francisco as test for your Houston example to provide for discussion here, but I have to get back to studying and testing of some other things.

What I would like to do is invite you to take the example that I provided with San Francisco and apply it to your scene and see what the results are with your test. My test could be much more fine tuned as it is very rough, it does not have any actual geographic landmass terrain to match the physical environmental conditions.

You have to remember, Maxwell Render is an unbiased high end render engine capable of the highest level in light simulation. As such, when making simulations you need to provide as an input as much as possible within time constraints and budget the most realistic data you can so that what you get as an output is somewhere in the ball park.

This is not like any other engine where there are elements of biasing to force the engine into something else, with Maxwell Render you are experimenting with real physical interactions with light which allows you a lot of freedom to experiment to achieve your artistic dreams in this virtual light simulator.

[juan]

Thanks a lot for such interesting comments.

This sky model asumes the observer is always located at altitude 0, and this is why we always see the pink-orange gradient in the horizon. Soon we will add an altitud parameter to control it. Besides, it is important to take in consideration what happens in real life, the ground is never perfectly flat, otherwise we always would see the red line in the horizon if we are at altitude 0. It is not common at all, so a scene like the one Tyrone has showed is more correct to avoid to see always below our own feet.

Regards,

Juan

[giacob]

i can say this:
a team of people i have been working already with maxwell altoghether whithout any hint or suggestion , looking at my new 1.5 renders at once pointed out this too much pinkish look of the sky compared to the previous renders and they didnt like it..

i think the same

[Tyrone Marshall]

i can say this:
a team of people i have been working already with maxwell altoghether whithout any hint or suggestion , looking at my new 1.5 renders at once pointed out this too much pinkish look of the sky compared to the previous renders and they didnt like it..

i think the same

I would have to evaluate the scene and parameters you and your team set for the examples you provided each other to evaluate before I could make a judgment on that assumption.

[giacob]

in any x,y, z , up to know, scene very similar to the previous one, sky look pinkier
.. frankly i cant understand why u can accept this. remark . is not so big fault... it was a spontaneous remark done whithout any malice.. so .. i am buffled at your strong reaction...

-,. perhaps we will got used to this new sky and in the end we will like it even more... fore sure is differente from the previuos,,, that can be denied....

[Tyrone Marshall]

in any x,y, z , up to know, scene very similar to the previous one, sky look pinkier
.. frankly i cant understand why u can accept this. remark . is not so big fault... it was a spontaneous remark done whithout any malice.. so .. i am buffled at your strong reaction...

-,. perhaps we will got used to this new sky and in the end we will like it even more... fore sure is differente from the previuos,,, that can be denied....

Giacob,

I can understand your notice of the sky colors and this okay. There were other remarks made which were not made by you. I am responding to those comments so that we can have a discourse about the observation rather than just simple commenting.

But in your comment about up and down, I do not agree with you because in reality there is a real x, y, and z. Why should a physically correct unbiased render engine be different?

[Nuno Faria]

Here is a website that can help to determine the turbidity/water/ozone of any location.

http://www.soda-is.com/eng/services/climat_eng.html

Best regards,
Nuno

[Maxer]

Juan and Tyrone,
I have done what you suggested I rendered my scene using Tyrone's settings for both Houston and San Francisco. As you can see the images are virtually the same and really don't look like Tyrone's test, this may be because he covered the pink in the sky up with his mountains I'm not sure. It doesn’t matter what time of day I set the pink remains in every iteration. I'm also confused now by Tyrone's inclusion of sea level and the adjusting of Turbidity, Ozone and Water. In all the previous versions of Maxwell none of these things needed to be adjusted in order to get a physically correct result.

Juan I understand what your saying however I live in one of the flattest areas in the US, where the only thing blocking my view to the horizon are overpasses and high rises and believe me when I say at 12:00pm I can look as far as the eye can see to the horizon and there is no pink in the sky. I don't know what to say other than the sky simply looks wrong regardless if it's scientifically correct or not. I also don't understand why we need to now have an altitude parameter, it seems like that is just a little more than we need in order to get a descent looking sky.

I'm not trying to be difficult I just want to figure out what is going on here and why my results are different from yours.



Houston:
-95.35
29.967
GMT -6
May 5, 2001
1pm
Trubidity: 3
Ozone: .35
Water: 2


San Fransisco:
-122.383
37.617
GMT -8
May 5, 2001
1pm
Trubidity: 3.5
Ozone: .328
Water: 1.73

[Tyrone Marshall]

Juan and Tyrone,
I have done what you suggested I rendered my scene using Tyrone's settings for both Houston and San Francisco. As you can see the images ....
Houston:
-95.35
29.967
GMT -6
May 5, 2001
1pm
Trubidity: 3
Ozone: .35
Water: 2
San Fransisco:
-122.383
37.617
GMT -8
May 5, 2001
1pm
Trubidity: 3.5
Ozone: .328
Water: 1.73

Hello Maxer,

Your example is a good. We just need to check some items. Please tell me what height your ground plane is?

I just check the sea level of Houston and it is at 43 ft which is about 9 feet lower than San Francisco.

I would say to start, your ground plane needs to be put at an elevation that corresponds to the scale of your scene at the sea level of Houston.

See this ref: http://en.wikipedia.org/wiki/Houston,_Texas

The next piece of the puzzle is your POV. How tall is the building in your scene?

Check out my rendering without the landmass, as you can see the landscape terrain were not covering up much of the horizon at all.

Please note without the terrain reflecting light, my camera exposure is off, but that is due to there being no earth now for my building.