Daz Tricks to remove sharp shadows from a scene when I'm using a HDRI map?

[lawfullame]

I use a HDRI map, which was taken at noon, so the sun is approximately at the top and makes a very sharp shadows .
I would like to simulate the setting sun and use the same HDRI map. The scene takes place in a garden, surrounded by a wall, so only trees behind the wall are visible from the HDRI map.
The problem is that even if I reduce the intensity of the map and background, the shadows still remain very sharp.
Any tricks to get rid of these sharp shadows?

So far, I'm trying to make a large partially transparent primitive and place it above the level of the camera's view, so that the primitive is not directly visible.
This removes the shadows on tehe garden, which are caused by direct sunlight from the HDRI scene.
Then I add some other light source that simulates the setting sun.

Do you have any better ways?

 

[mickydoo]

Why can't we quote/reply in here?

So far, I'm trying to make a large partially transparent primitive and place it above the level of the camera's view, so that the primitive is not directly visible.

Furthering that idea, I use a big fake tree sometimes. Put a fairly big plane in the scene and google tree vector or just vectors, you can actually make them easily enough in DAZ from any sort of asset if you want. The googled vectors will be backwards to what you want, they are black on a white (or clear background) you have to invert them in photoshop or something so it's white on a black background. In the surfaces tab apply it to the cutout capacity bit, not the normal base colour. IRAY will ignore anything black and cast a shodow off anything white.

 

[lawfullame]

Why can't we quote/reply in here?


Furthering that idea, I use a big fake tree sometimes. Put a fairly big plane in the scene and google tree vector or just vectors, you can actually make them easily enough in DAZ from any sort of asset if you want. The googled vectors will be backwards to what you want, they are black on a white (or clear background) you have to invert them in photoshop or something so it's white on a black background. In the surfaces tab apply it to the cutout capacity bit, not the normal base colour. IRAY will ignore anything black and cast a shodow off anything white.

The quote works for me normally. I'm not sure I understand what you're doing. What is the advantage of a fake tree over a primitive like a plane or cube? Do you use this when you want the shadows of fake trees?

 

[mickydoo]

The quote works for me normally. I'm not sure I understand what you're doing. What is the advantage of a fake tree over a primitive like a plane or cube? Do you use this when you want the shadows of fake trees?

Its working now, fucked if I know.

But yeah I use it to cast a shadow over the scene, so instead of having a brightly lit area it's shaded.
Like this

Lifting it up will make the shadow longer (or scaling it up), so in theory, you could cast a tree shadow over your entire scene.

 

[lawfullame]

Its working now, fucked if I know.

But yeah I use it to cast a shadow over the scene, so instead of having a brightly lit area it's shaded.
Like this
View attachment 785413
Lifting it up will make the shadow longer (or scaling it up), so in theory, you could cast a tree shadow over your entire scene.

Well, in fact, I need the exact opposite, to prevent objects from casting shadows where the light source is an HDR map.
So I'm looking for ways to cover the main light source in the HDR map without making the result look too weird.
But these trees are quite a nice trick, albeit for a different problem.

 

[Rich]

Why can't we quote/reply in here?

For some reason, known only to the admins, you can quote/reply to any post in a thread EXCEPT the OP. Odd.

 

[DonJoe]

Well, in fact, I need the exact opposite, to prevent objects from casting shadows where the light source is an HDR map.
So I'm looking for ways to cover the main light source in the HDR map without making the result look too weird.
But these trees are quite a nice trick, albeit for a different problem.

Just to get you right, you want to add objects to the scene (with the HDRI used as BG) and avoid these casting sharp shadows ?

Or do you just want to use the HDRI as a lighting source ?

Here's a render with a HDRI from HDRI Heaven, first render original, second one sun covered with a nearby part of the heaven (GIMP could handle that e.g.).

 

[lawfullame]

Just to get you right, you want to add objects to the scene (with the HDRI used as BG) and avoid these casting sharp shadows ?

Or do you just want to use the HDRI as a lighting source ?

Here's a render with a HDRI from HDRI Heaven, first render original, second one sun covered with a nearby part of the heaven (GIMP could handle that e.g.).

View attachment 785799

View attachment 785801

Yes. I'm adding objects to the scene and I want them not to cast sharp shadows.

The ground on the HDRI map is not visible, because my scene includes a house with a garden, which is not part of the HDRI map. The only part of the HDRI map that is directly visible are the tops of the trees and the sky behind the walls.
The sun on the HDRI map causes objects to cast sharp shadows.
The HDRI MAP was taken at noon and I want to make a scene that looks like an afternoon. So the main light source can't be right up.
Here are two examples. I let the rendering run for only a few iterations, so the images are very grainy.
Image 1. The only source of light is the HDRI map.


Image 2. I block the direct sun using a large plane located at the top outside the view of the camera. I added another source, a distant light from the left.

 

[79flavors]

Why can't we quote/reply in here?

The quote works for me normally. I'm not sure I understand what you're doing.

The admins changed the site back in July to avoid moderation problems when new users were quoting the first post in the release forums. So we can quote the 2nd post and every one after it... just not the first.
They have said they are looking to make it apply to only the releases forum rather than everywhere... but no eta on when.

 

[DonJoe]

Okay, first pic is using the original HDRI, taken at (high) noon:

You must be registered to see the links

Second pic uses the modified (GIMP) HDRI with modified white point:



Here's a jpeg how the modified (sun removed with the healing brush) HDRI looks like:

 

[lawfullame]

Okay, first pic is using the original HDRI, taken at (high) noon:

You must be registered to see the links

View attachment 786084

Second pic uses the modified (GIMP) HDRI with modified white point:

View attachment 786096

Here's a jpeg how the modified (sun removed with the healing brush) HDRI looks like:

View attachment 786123

Removing the sun from the HDRI in GIMP is a good idea. Better than using a primitive to block sunlight. Then it is easier to use and adjust the distant light.

 

[mickydoo]

Removing the sun from the HDRI in GIMP is a good idea. Better than using a primitive to block sunlight. Then it is easier to use and adjust the distant light.

You can even make a fake sun in the HDRI in any position you want, the issue is though, removing or moving the sun changes the shadow of your characters and props, but not on the HDRI itself, so the shadows look different in the scene.

 

[lawfullame]

You can even make a fake sun in the HDRI in any position you want, the issue is though, removing or moving the sun changes the shadow of your characters and props, but not on the HDRI itself, so the shadows look different in the scene.

I think adding another light source such as a distant light or some sphere with an emissive surface is better than editing HDRI directly and adding sun to HDR map.
Of course, the lighting of the HDRI map does not match the lighting of the scene. But I'm not trying to make the lighting of HDRI map and scene 100% matching. I can play with the intensity of the environment and map, use DoF etc.
And I could also have 4 or 5 variants of the hdri map, where I will adjust the colors a bit, I mean useing some filter that changes colors to warmer for the evening scene etc..

Any advice on what color changes to make in the GIMP so that the map, which was taken at noon, would give the impression of a late afternoon? I know that the direction of light is a problem, but I'm not trying to have an ultra-realistic scene.

 

[DonJoe]

You could change the White Point in Render Settings > Tone Mapping > White Point

First one is the original WP, second is a blueish one....





But tbh, if you just want this special HDRI to be part of the background, I would render it without anything else as BG.

Then without drawing the dome, render all your scene objects with the lighting you want and save it as png to preserve alpha transparancy.

And then mix it all together in PW, so you are able to adjust the color, brightness, sharpness and whatsoever of your piece of BG perfectly.


First one is with the HDRI above as BG and lighting source, second one is rendered with a sunset HDRI as lighting source for the scene objects (without drawing the dome) and then assembled and adjusted in PW.