HDRI domes and interior lighting

bwise1701

When one is rendering with only an HDRI map , ie no scene lights is there a way to visualize the dome (before rendering) in order to see where the sun is in the map and therefore reposition it - right now I have to render and guess and render again.

 

Also for interiors my HDRI domes tend to give very dark rooms and very bright hot light thru the window. I would like and expect a bit more bounce in the room particularly with wite walls - is there a way to balance things out a bit more? I'm trying different ISO and shutter speed settings and that helps but still get blown out hot spots - I notice a setting in IRay optimizations - Architectural sampling - does anyone know what that affects?

thanks

CrissieB

Hi bwise1701,

You ask:

 

bwise1701 said:

When one is rendering with only an HDRI map , ie no scene lights is there a way to visualize the dome (before rendering) in order to see where the sun is in the map and therefore reposition it - right now I have to render and guess and render again.

 

Also for interiors my HDRI domes tend to give very dark rooms and very bright hot light thru the window. I would like and expect a bit more bounce in the room particularly with wite walls - is there a way to balance things out a bit more? I'm trying different ISO and shutter speed settings and that helps but still get blown out hot spots - I notice a setting in IRay optimizations - Architectural sampling - does anyone know what that affects?

thanks

As to the sun position, you can see that by looking at the HDRI image itself. Click on it in the Render Settings Environment panel, you'll see the HDRI image. Mentally divide the image into four vertical quadrants, like this:

If the brightest spot in your HDRI image is in the same quadrant as the white circle in the diagram above, then your sun (or moon) is in the Back sky (in DAZ terms), lighting the Front of your set.

You can use Render Settings > Environment > Dome Rotation to place your sun where you want it. If you set Dome Rotation to 90 degrees, the sun will move one quadrant to the right on that diagram: Front to Right, Right to Back, Back to Left, or Left to Front, depending on where your sun began. Setting Dome Rotation to 180 degrees will move the sun two quadrants: Front to Back, Right to Left, Back to Front, or Left to Right. Setting Dome Rotation to 270 degrees (or -90 degrees) will move your sun one quadrant to the left​ on that diagram: Front to Left, Right to Front, Back to Right, or Left to Back.

You can control the brightness of the sunlight with the Environment Intensity and/or Environment Map settings. Note that these multiply​ ... so if Intensity is at 1 and Map is at 2, the net illumination is 2. If you move Intensity to 2, with the Map still at 2, the net illumination is 4. If you move Intensity to 0.5, with the Map still at 2, the net illumination is 1.

As for reflections inside your room, check the Surfaces tab for your interior wall, ceiling, and floor materials. They may be more light-absorbent than you want.

Even so, rooms lighted only by sunlight through a single window -- no interior light -- will have very stark contrast. Your eyes can somewhat adjust for that in real life, but most offices have interior lights on during the day for a reason. And a camera won't adjust for it at all. So yes, you'll have to adjust for that, with Tone Mapping in your render settings and/or by adjusting the contrast in postwork.

I hope this helps,

Crissie

fastbike1

You will also probably have to add some lighting to "fake" the results. Similar to stage/movie lighting tricks.

You can also put a point light outside the window, but you will need to increase the lumen setting by a factor of 10000 (due to the internal measurements untis difference between Daz and Nvidia: cm2 to m2)

prixat

The Architectural sampler will help in this situation, but may add a time penalty.

As other methods for getting more light into the room have already been mentioned, I'd add the use of Light Portals to the list, to speed up the render.

Put a light portal in the window or just outside it and that will tell Iray to concentrate it's calculations on the part of the dome that can 'see' the portal and not waste time calculating the portion of the dome that would never get into the room.

bwise1701

prixat said:

The Architectural sampler will help in this situation, but may add a time penalty.

As other methods for getting more light into the room have already been mentioned, I'd add the use of Light Portals to the list, to speed up the render.

Put a light portal in the window or just outside it and that will tell Iray to concentrate it's calculations on the part of the dome that can 'see' the portal and not waste time calculating the portion of the dome that would never get into the room.

I'm unfamiliar with light portals -  how are those defined?

 

nonesuch00

Ideally DAZ Studio should have a dome with one of the exposures of the HRDI image mapped to it before you render and allow the user to input a date & time & GPS cooridinates for the HRDI in use.

Maybe there is HRDI preview SW that can do this?

Richard Haseltine

bwise1701 said:

prixat said:

The Architectural sampler will help in this situation, but may add a time penalty.

As other methods for getting more light into the room have already been mentioned, I'd add the use of Light Portals to the list, to speed up the render.

Put a light portal in the window or just outside it and that will tell Iray to concentrate it's calculations on the part of the dome that can 'see' the portal and not waste time calculating the portion of the dome that would never get into the room.

I'm unfamiliar with light portals -  how are those defined?

Create a new spotlight, in its paramaters enable Photometric mode, set its shape to rectangular and size it to cover the opening you want to direct the lightt hrough, then enable the Portal setting.

CrissieB

Hi nonesuch00,

nonesuch00 said:

Ideally DAZ Studio should have a dome with one of the exposures of the HRDI image mapped to it before you render and allow the user to input a date & time & GPS cooridinates for the HRDI in use.

Maybe there is HRDI preview SW that can do this?

You can do the first part by switching your DAZ Viewport to NVIDIA Iray mode. That will show the HDRI, and any shadows it casts.

Once you know the default azimuth (compass angle) for a given HDRI's sun/moon, you can look here for the sun or here for the moon to get the actual solar/lunar azimuth for a given date-time-location. Then use Render Settings > Environment > Dome Rotation to match your HDRI's solar/lunar azimuth to the actual azimuth.

Alas, so far as I know, there's no way to match the solar/lunar elevation (angle above the horizon).

I hope this helps,

Crissie

nonesuch00

cris_brown said:

Hi nonesuch00,

nonesuch00 said:

Ideally DAZ Studio should have a dome with one of the exposures of the HRDI image mapped to it before you render and allow the user to input a date & time & GPS cooridinates for the HRDI in use.

Maybe there is HRDI preview SW that can do this?

You can do the first part by switching your DAZ Viewport to NVIDIA Iray mode. That will show the HDRI, and any shadows it casts.

Once you know the default azimuth (compass angle) for a given HDRI's sun/moon, you can look here for the sun or here for the moon to get the actual solar/lunar azimuth for a given date-time-location. Then use Render Settings > Environment > Dome Rotation to match your HDRI's solar/lunar azimuth to the actual azimuth.

Alas, so far as I know, there's no way to match the solar/lunar elevation (angle above the horizon).

I hope this helps,

Crissie

Thanks those are nice but DAZ 3D will need to do a preview mode in OpenGL format for my computer to handle it. The websites are cool.