DC3 and HDR

[stebbo]

Date: 8/9/2007 9:38:28 PM
Author: Garry H (Cut Nut)
Here is a diamonds eye view of one of my staff (programed into DiamCalc as an observer) in a ball room (from a 360 degree high dynamic range HDR) photo. The little specs are the ETAS - they show the places where lights need to be in order to cause a sparkle in the diamond.

Kewl?

I didn't want to hijack another thread, but am interested to know if you've interpreted this correctly. I haven't played with DC3 yet but regardless, I can't make sense of what you say.

This sounds more reasonable to me:

A HDR image file of the room you see roughly depicted above (but minus the ETAS flashes and minus your staff member) was supplied as the lighting environment for the render here. It gets laid on the inside of a hemisphere cupping the diamond (if it is a spherical HDR file) and all the colors and intensities in the image simulate light sources for the computer render. The HDR method of lighting is less accurate but quicker than 3d modeling the whole room and specify lighting, but less accurate than just specifying lighting like in previous DiamCalcs.

The image of your staff members looks to be an additional, user supplied image that gets merged in with the generic HDR file. This allows the user to easily control what the observer looks like and where they are position) without having to create and supply a new HDR file each time (which is a bit of an effort with the typical digital camera).


Finally, the bottom photo is, as you say, how you would see the room if you were sitting inside the diamond, but the ETAS flashes are the resultant light dollops that would appear on the inside of an imaginary black dome cupping the diamond. If a small dome is used, the light is tighter, if a big dome is specified, the colors in the light separate more. Maybe you meant "the ETAS flashes are where an (invisible) observer needs to be to see the intense white or colored light representatively shown here".

 

[Garry H (Cut Nut)]

see comments

Date: 8/10/2007 12:09:55 AM
Author:stebbo

Date: 8/9/2007 9:38:28 PM
Author: Garry H (Cut Nut)
Here is a diamonds eye view of one of my staff (programed into DiamCalc as an observer) in a ball room (from a 360 degree high dynamic range HDR) photo. The little specs are the ETAS - they show the places where lights need to be in order to cause a sparkle in the diamond.

Kewl?

I didn''t want to hijack another thread, but am interested to know if you''ve interpreted this correctly. I haven''t played with DC3 yet but regardless, I can''t make sense of what you say.

This sounds more reasonable to me:

A HDR image file of the room you see roughly depicted above (but minus the ETAS flashes and minus your staff member) was supplied as the lighting environment for the render here. It gets laid on the inside of a hemisphere cupping the diamond (if it is a spherical HDR file) and all the colors and intensities in the image simulate light sources for the computer render. The HDR method of lighting is less accurate but quicker than 3d modeling the whole room and specify lighting, but less accurate than just specifying lighting like in previous DiamCalcs. It is not a hemisphere - it is a total 360 x 360 image including the floor which in the case above you can see in the upper left window is a dark brownish colour. The intensities are not normal camera intensities - the bright sources are maybe 5 or 10 times brighter than plain white stebbo - they are as if you were in a real room with real lights. These images can cost many thousands of dollarsbecause they are taken with very special cameras and software that merges maybe 1000 images (I am gusessing).

The image of your staff members looks to be an additional, user supplied image that gets merged in with the generic HDR file. This allows the user to easily control what the observer looks like and where they are position) without having to create and supply a new HDR file each time (which is a bit of an effort with the typical digital camera). There are instructions so you can add your own image - it needs to have the background cut away and be just a normal image from any camera.


Finally, the bottom photo is, as you say, how you would see the room if you were sitting inside the diamond, but the ETAS flashes are the resultant light dollops that would appear on the inside of an imaginary black dome cupping the diamond. If a small dome is used, the light is tighter, if a big dome is specified, the colors in the light separate more. Maybe you meant ''the ETAS flashes are where an (invisible) observer needs to be to see the intense white or colored light representatively shown here''. mostly correct, except this is reversed - ETAS is the potential for a light to shine from a facet - so if there is a light where one of the flashes hits the imaginary dome - then the diamond would have a sparkle - if the sparkle is strongly dispersed then the chance to see fire is greater.

 

[strmrdr]

Im bummed out cuz I have to get a new puter to run dc3 :{
waaaahhhhhh lol

 

[Garry H (Cut Nut)]

yes Storm, unfortunately it will only do the High Dynamic Range imaging with a state of the art graphics system

 

[stebbo]

Date: 8/10/2007 1:05:44 PM
Author: strmrdr
Im bummed out cuz I have to get a new puter to run dc3 :{

waaaahhhhhh lol

You''re bummed out because you have to get a new computer?

 

[stebbo]

Date: 8/10/2007 1:52:48 AM
Author: Garry H (Cut Nut)
It is not a hemisphere - it is a total 360 x 360 image including the floor which in the case above you can see in the upper left window is a dark brownish colour

Quite right, I can imagine a diamond light study should use full spherical lighting. Other apps (computer games, architectural visualizations...) just a super wide-angle lens or a 360 deg panorama for simplicity and faster rendering.

The intensities are not normal camera intensities - the bright sources are maybe 5 or 10 times brighter than plain white stebbo - they are as if you were in a real room with real lights. These images can cost many thousands of dollarsbecause they are taken with very special cameras and software that merges maybe 1000 images (I am gusessing).

Not a bad guess, they are created either with a single shot from a camera with a higher dynamic range sensor (more levels of brightness from the darkest shadows through to the brightest highlights) OR a typical digital camera taking multiple shots at different exposures and then having software combine the result together. It''s a bit like the technique photographers do on a sunny day when they cut and paste the sky from a shorter exposed shot with the subject from another, longer exposed shot, except HDR merges the whole image - no cutting and pasting. The actual rendering software then is responsible for how bright to make the brightest white, as an HDR image contain no real-world physical luminence data, just relative brightnesses. To get the panoramic nature of the image, they either simply shoot a mirrored ball, use a rotating camera, or stitch multiple panned images together.

ETAS is the potential for a light to shine from a facet - so if there is a light where one of the flashes hits the imaginary dome - then the diamond would have a sparkle

Hmmmm, I haven''t got it yet, but I''ll continue thinkin'' about it, in reverse. Can''t see where the observer comes in to it yet, but maybe that''s the whole point. Maybe it encapsulates observers at every position and thus becomes observer independent.

 

[strmrdr]

Date: 8/10/2007 9:35:00 PM
Author: stebbo

Date: 8/10/2007 1:05:44 PM
Author: strmrdr
Im bummed out cuz I have to get a new puter to run dc3 :{

waaaahhhhhh lol

You're bummed out because you have to get a new computer?

Well this one is only around 6 years old
My oldest in use computer is 12 years old
So plenty of life left yet
I don't believe in buying new computers until the old one blows up or is totally unusable.
It still works fine for photoshop and compiling software.
and
and
and
no $$ for a new puter :{

 

[stebbo]

Date: 8/10/2007 7:55:55 PM
Author: Garry H (Cut Nut)
yes Storm, unfortunately it will only do the High Dynamic Range imaging with a state of the art graphics system

Vladimir mentioned to me that a Core 2 Duo with a GeForce 7600 graphics card will run the same speed using HDRI as you're used to DC2.8 running. But that was 6 months ago - things may have changed.

Now of course there's a huge range of Core 2 Duo's, but they really are not expensive, nor state of the art. Entry level Core 2 Duo processor is about $120, top is in the 400's. Motherboard's - $60 entry level to $350 for top. 7600 graphics cards are mid-range consumer cards, ranging from about $75 to $150. A good system will not be prohibitively expensive.

Also Garry, is there going to be a non-HASP DC3? What's the upgrade procedure and can one convert from non-HASP to HASP (the computer id licensing method is a pain in the butt for someone like me who reinstalls Windows every 6 months).

 

[Garry H (Cut Nut)]

Date: 8/10/2007 9:51:04 PM
Author: stebbo

ETAS is the potential for a light to shine from a facet - so if there is a light where one of the flashes hits the imaginary dome - then the diamond would have a sparkle

Hmmmm, I haven''t got it yet, but I''ll continue thinkin'' about it, in reverse. Can''t see where the observer comes in to it yet, but maybe that''s the whole point. Maybe it encapsulates observers at every position and thus becomes observer independent.

The view point is from a dot placed in the center of an observers eye. The spots are where a light would need to be for a sparkle to ''hit'' you between the eyes. Reverse your thinking Stebbo

 

[stebbo]

Date: 8/10/2007 10:27:39 PM
Author: Garry H (Cut Nut)

The view point is from a dot placed in the center of an observers eye. The spots are where a light would need to be for a sparkle to 'hit' you between the eyes. Reverse your thinking Stebbo

[/quote]

The reverse bit is no problem, it's when you say "...sparkle to hit you between the eyes" which suggests to me a predefined viewing position. A light positioned anywhere will be released in multiple places and directions, causing sparkles somewhere (of course depending on how intense a sparkle must be to be called a sparkle). From what you say, I understand an ETAS image indeed only shows us the lighting positions that return light of sufficient intensity to an observer at a predefined position. I was hoping it showed us the lighting positions that return light of sufficient intensity, somewhere, something much more practical.

 

[Garry H (Cut Nut)]

Date: 8/11/2007 11:42:31 PM
Author: stebbo

Date: 8/10/2007 10:27:39 PM
Author: Garry H (Cut Nut)

The view point is from a dot placed in the center of an observers eye. The spots are where a light would need to be for a sparkle to ''hit'' you between the eyes. Reverse your thinking Stebbo

The reverse bit is no problem, it''s when you say ''...sparkle to hit you between the eyes'' which suggests to me a predefined viewing position. A light positioned anywhere will be released in multiple places and directions, causing sparkles somewhere (of course depending on how intense a sparkle must be to be called a sparkle). From what you say, I understand an ETAS image indeed only shows us the lighting positions that return light of sufficient intensity to an observer at a predefined position. I was hoping it showed us the lighting positions that return light of sufficient intensity, somewhere, something much more practical.


[/quote]
No, the reverse issue is still a problem for you. The sprkels show the potential for light to hit the red dot which you can set on the observer. The observer position is shown on the right. The sparkles ARE the direction that a light must be in for an observer to be hit in the chosen spot, and are also related to the pupil size and other predtemined factors. There are very good reasons why ETAS is this way and not the way that you prefer.
But ETAS is also abole to habdle the size, position and distance of a light source and estimate the probability and hence the various types of sparkle potential for any cut of diamond for any given observer variables (pupil, head and body size amd observer distance etc.

 

[Garry H (Cut Nut)]

oops