|
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 07/08/2018 11:51, clipka wrote:
> Am 07.08.2018 um 12:33 schrieb Stephen:
>
>> A close up of the terminator on the Ringworld.
>> The area light does make a difference.
>> Using
>> light_source { // Light_Source2
>> < 0.000000, 0.000000, 0.000000 >, colour rgb <1.000,1.000,1.000>*1.500
>> area_light <3.400000,0.000000,0.000000>, <0.000000,3.400000,0.000000>,
>> 23, 23
>>
>> circular
>> orient
>> adaptive 5
>
> And it better does. You don't want the light to blink off
> instantaneously - you do want some twilight time.
>
That is the whole idea, I believe. ;)
As for maths the area_light axis vectors should be doubled to 6.8 not 3.4
I was thinking radius as opposed to diameter.
--
Regards
Stephen
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 07/08/2018 12:07, Thomas de Groot wrote:
> On 7-8-2018 12:51, clipka wrote:
>> Am 07.08.2018 um 12:33 schrieb Stephen:
>>
>>> A close up of the terminator on the Ringworld.
>>> The area light does make a difference.
>>> Using
>>> light_source { // Light_Source2
>>> < 0.000000, 0.000000, 0.000000 >, colour rgb
>>> <1.000,1.000,1.000>*1.500
>>> area_light <3.400000,0.000000,0.000000>,
>>> <0.000000,3.400000,0.000000>,
>>> 23, 23
>>>
>>> circular
>>> orient
>>> adaptive 5
>>
>> And it better does. You don't want the light to blink off
>> instantaneously - you do want some twilight time.
>>
>
> I agree. What I meant earlier was that, with the camera at /planetary/
> distances from the ring, the penumbra would hardly be visible. Up close,
> and more so on the ring surface, of course the penumbra matters.
> However, if the area_light is set while the camera is at a /planetary/
> distance, it will most probably be grossly exaggerated because otherwise
> you would not be able to see it properly in a render.
>
Do you mean that the penumbra would need to be exaggerated so it can be
seen?
I thought that too but when I created two big sticks located at opposite
sides of the star and clipping the same edge of a shadow square. The
divergence at the ring was quite large.
I might try moving the shadow square radius back to the quoted radius
and adjust the length of the shadow square to get equal day/night.
This image was taken from slightly beyond the other side of the ring and
above a bit.
--
Regards
Stephen
Post a reply to this message
Attachments:
Download 'ring_3c_0000.png' (17 KB)
Preview of image 'ring_3c_0000.png'
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 07/08/2018 12:23, Stephen wrote:
> I might try moving the shadow square radius back to the quoted radius
> and adjust the length of the shadow square to get equal day/night.
As threatened. :-)
Twilight is less obvious.
--
Regards
Stephen
Post a reply to this message
Attachments:
Download 'ring_4_0000.png' (14 KB)
Preview of image 'ring_4_0000.png'
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Le 18-08-07 à 06:33, Stephen a écrit :
> On 07/08/2018 11:29, Stephen wrote:
>> No, don't follow my maths.
>>
>> Using the data from this site. I did a quick model.
>> http://www.alcyone.com/max/reference/scifi/ringworld.html
>> I adjusted the Shadow square ring radius until the day/night cycle
>> looked equal.(multiplied the radius by 0.587587699)
>
> A close up of the terminator on the Ringworld.
> The area light does make a difference.
> Using
> light_source { // Light_Source2
> < 0.000000, 0.000000, 0.000000 >, colour rgb <1.000,1.000,1.000>*1.500
> area_light <3.400000,0.000000,0.000000>,
> <0.000000,3.400000,0.000000>, 23, 23
>
> circular
> orient
> adaptive 5
>
The 23, 23 get bumped up to 33, 33
adaptive 5 mean start at subdivision 5, or start with 33, 33 samples.
This effectively disable the adaptive optimization.
In the present case, adaptive 0 is good.
adaptive 0 start at 2 by 2
adaptive 1 start at 3 by 3
adaptive 2 start at 5 by 5
adaptive 3 start at 9 by 9
adaptive 4 start at 17 by 17
adaptive 5 start at 33 by 33
adaptive 6 start at 65 by 65
...
You need a number of samples at least 2 step up to get some appreciable
benefit. For adaptive 0, use at least 5 by 5, and 9 by 9 or more in most
cases.
For adaptive 1, better to start around 17 by 17.
For adaptive 5, you start to see an improvement around 129 by 129...
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 07/08/2018 15:33, Alain wrote:
> Le 18-08-07 à 06:33, Stephen a écrit :
>>
>> A close up of the terminator on the Ringworld.
>> The area light does make a difference.
>> Using
>> light_source { // Light_Source2
>> < 0.000000, 0.000000, 0.000000 >, colour rgb <1.000,1.000,1.000>*1.500
>> area_light <3.400000,0.000000,0.000000>,
>> <0.000000,3.400000,0.000000>, 23, 23
>>
>> circular
>> orient
>> adaptive 5
>>
>
> The 23, 23 get bumped up to 33, 33
>
> adaptive 5 mean start at subdivision 5, or start with 33, 33 samples.
> This effectively disable the adaptive optimization.
> In the present case, adaptive 0 is good.
>
> adaptive 0 start at 2 by 2
> adaptive 1 start at 3 by 3
> adaptive 2 start at 5 by 5
> adaptive 3 start at 9 by 9
> adaptive 4 start at 17 by 17
> adaptive 5 start at 33 by 33
> adaptive 6 start at 65 by 65
> ....
>
> You need a number of samples at least 2 step up to get some appreciable
> benefit. For adaptive 0, use at least 5 by 5, and 9 by 9 or more in most
> cases.
> For adaptive 1, better to start around 17 by 17.
> For adaptive 5, you start to see an improvement around 129 by 129...
Thanks Alain, I seldom use area lights and this is the first time I have
used adaptive.
When you said samples is that what the offline help names Size_1 &
Size_2, in the line;
AXIS_1_VECTOR, AXIS_2_VECTOR, Size_1, Size_2?
--
Regards
Stephen
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 8/7/2018 4:20 AM, Stephen wrote:
>> That, or scale down the area_light's effective surface. At this
>> planetary scale the area effect would be hardly noticeable imo.
>>
>
> A point light gives the same result.
>
I tried a point light, and the day/night cycles were equal. But Niven
did specify the size of the star, and I checked my other numbers against
his and they match.
Mike
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 8/7/2018 7:09 AM, Stephen wrote:
> That is the whole idea, I believe. ;)
>
> As for maths the area_light axis vectors should be doubled to 6.8 not 3.4
> I was thinking radius as opposed to diameter.
>
>
You just reminded me that I used the sun radius instead of diameter for
the area light axes.
When instead using the diameter, I get some fuzziness but no real "night".
Sorry, Niven. Your math is bad.
Mike
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 07/08/2018 20:28, Mike Horvath wrote:
> On 8/7/2018 7:09 AM, Stephen wrote:
>> That is the whole idea, I believe. ;)
>>
>> As for maths the area_light axis vectors should be doubled to 6.8 not 3.4
>> I was thinking radius as opposed to diameter.
>>
>>
>
> You just reminded me that I used the sun radius instead of diameter for
> the area light axes.
>
I now feel better. ;)
> When instead using the diameter, I get some fuzziness but no real "night".
>
You don't have an "ambient" in there? (Before Clipka says anything. ;) )
> Sorry, Niven. Your math is bad.
Funnily enough, I did not notice that when I read the books. ;)
It is PovRay's fault. It is too realistic. :)
I think it is better to bring the shadow shields nearer the sun, for the
data I found.
This last image (I promise) using Alain's settings, has a stary
background to show that the night part of the ring is occluding the stars.
BTW Thanks for starting the thread. It has been a distraction for me
when I don't feel up to starting a new project.
--
Regards
Stephen
Post a reply to this message
Attachments:
Download 'ring_3d_0000.png' (16 KB)
Preview of image 'ring_3d_0000.png'
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 8/7/2018 5:52 PM, Stephen wrote:
> Funnily enough, I did not notice that when I read the books. ;)
> It is PovRay's fault. It is too realistic. :)
>
> I think it is better to bring the shadow shields nearer the sun, for the
> data I found.
>
> This last image (I promise) using Alain's settings, has a stary
> background to show that the night part of the ring is occluding the stars.
>
> BTW Thanks for starting the thread. It has been a distraction for me
> when I don't feel up to starting a new project.
>
>
Hold on. I just noticed I wasn't using the correct sizes for the shadow
squares. And I had 40 of them instead of 20. I will need to redo them.
Mike
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 7-8-2018 14:01, Stephen wrote:
> On 07/08/2018 12:23, Stephen wrote:
>> I might try moving the shadow square radius back to the quoted radius
>> and adjust the length of the shadow square to get equal day/night.
>
> As threatened. :-)
>
> Twilight is less obvious.
>
Yes, but I think it is looking natural from that distance. On the ring,
twilight would be gradual, as expected.
--
Thomas
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|