I have a photo on a background plane but it is near to the actual objects I am using in the render. The problem is that there are shadows that fall upon the backdrop. Moving the background plane further back prevents the shadows falling but then the photo resolution starts to break down and become blocky as the background plane has to increase in size too much to cover the same area in the render.

My question is that is there a way of preventing shadows from falling on an object like there is a method of stopping an object casting shadows. I attach a render of the problem. My intial thoughts were to create two renders, one with shadows and one without and then use an art program to remove the bits I don't want - rather time consuming. Is there a quick way? An thoughts or suggestions? Thanks in advance.

You can set up your background texture as shown in the picture.

This allows the background to not be effected by the lighting in your scene.

Also keeping the image plugged into the diffuse node allows the image to be seen in Preview mode

You can also set your background to not cast shadows.

You can turn off shadows in your render settings. That will turn off all shadows though.
The best way I have found to do this is to use no back ground, render your image, save to .PNG format which will make the BG transparent then apply the BG in photo shop or what ever program you use that can use layers.

you can also connect the image to the alternative diffuse

Quote - You can turn off shadows in your render settings. That will turn off all shadows though.
The best way I have found to do this is to use no back ground, render your image, save to .PNG format which will make the BG transparent then apply the BG in photo shop or what ever program you use that can use layers.

Why do you call that the "best" way, in comparison to simply connecting the image to Ambient or Alternate_Diffuse, and setting the Diffuse_Value = 0?

First of all, that's several extra steps involving saving, switching apps, and loading, then saving the composite again.

Second, if any of the foreground objects are reflective, they will not show any of the background in the rendered objects unless you include the background in the render. I understand not all renders are reflective, but if they are, you lose that ability.

Have a look at this image from my gallery:

http://www.renderosity.com/mod/gallery/full.php?image_id=1840594

There is a background prop with a sky/cloud photo behind the airplane. If you look closely, much of the realism comes from the reflections of those clouds on the planes surfaces. If you did the composite of that in post, the plane would look fake.

Quote - > Quote -

There is a background prop with a sky/cloud photo behind the airplane. If you look closely, much of the realism comes from the reflections of those clouds on the planes surfaces. If you did the composite of that in post, the plane would look fake.

sometimes you render more parts so that you can then experiment with colors and do some small changes.

if we dont use the ENVsphere we can not have physical correct reflections. what i would do for a render like you posted:
-render the plane plus the ENVsphere. that way i get real reflections
-turn of ENV sphere. make BG white and turn of all lights. render. i have now a matte.

now i can go in photoshop and open this all together. i duplicate the layer and on the second layer i erase with the  ''matte''  the background. now i have two seperate pics. i have now full control. if maybe teh lighting was not good enough i can now do some small changes to really make sure that the render fits with the BG. i can now replace the BG with a similar pic that also has clouds.
sometimes we dont get very big and clean  pics for 360 enviorments. here i could now blur it a little and made some simple DOF.  it all depends.
it is extra work but you have more control for last changes. at the end of the day its not about how fast you can post the render but how good it is.

ILM and Digital Domain are always trying to get almost everything in the render. they dont like to do  touch ups . but they have better tools.

I used both the EnvSphere and a background rectangle. The sphere had a sky as well, but as you say it did not have enough detail for the large render I wanted. So the background rectangle provided the detail necessary for direct viewing. Also, realize that because of the Fresnel effect, only surfaces pointing away from the camera (up, down, etc.) really show any reflection. All those surface reflections hit the background rectangle, as it was much larger than my render. Only a tiny bit of reflection came from the EnvSphere.

You could probably just import a background from the menu. No shadows at all that way and no props to worry about, except the ones on the bottom, where they would fall naturally anyway (except if you are supposed to be close to a wall or something). Just move the camera in or out to position your subject on the background.

Or if you do it the PNG way, use the BG import to position, then turn off the background picture, render and drop it into Photoshop over the background. I use a layer style with a colored inner glow to simulate the lighting colors if I don't get the lighting effect I want on the render itself and a slight dropshadow with a wide spread to add depth. I sometimes add a gradient layer style as well if needed. Either way you can change the layer style as much as you want. You can also hue adjust the BG in Photoshop too independantly of the front PNG layer, so you can change the whole tone of the image without re-rendering anything. Takes all of about 10 minutes of work.

My 2 cents....might help someone out :)

Thank you all for your ideas. I have decided to keep the background within the render rather than have lots of post work on the image. I am very much of the frame of mind to do as much as possible in poser and in one render - it makes me think a bit more of how to achieve what I have in my mind's eye. I like the challenge.

I chose to put the background image (on its plane object) further back. It is a balancing act between resolution and quality. Time consuming postwork is a last resort for me if I cannot think of another way to do it.

Quote - I chose to put the background image (on its plane object) further back. It is a balancing act between resolution and quality. Time consuming postwork is a last resort for me if I cannot think of another way to do it.

I don't understand, did ice-boy or my suggests to change how the texture was set up for your background plane texture not work with your background plane.  If so can you show a picture of how the texture was set up so we can so what might be wrong.

Quote - > Quote - You can turn off shadows in your render settings. That will turn off all shadows though.

The best way I have found to do this is to use no back ground, render your image, save to .PNG format which will make the BG transparent then apply the BG in photo shop or what ever program you use that can use layers.

Why do you call that the "best" way, in comparison to simply connecting the image to Ambient or Alternate_Diffuse, and setting the Diffuse_Value = 0?

First of all, that's several extra steps involving saving, switching apps, and loading, then saving the composite again.

Second, if any of the foreground objects are reflective, they will not show any of the background in the rendered objects unless you include the background in the render. I understand not all renders are reflective, but if they are, you lose that ability.

Have a look at this image from my gallery:

http://www.renderosity.com/mod/gallery/full.php?image_id=1840594

There is a background prop with a sky/cloud photo behind the airplane. If you look closely, much of the realism comes from the reflections of those clouds on the planes surfaces. If you did the composite of that in post, the plane would look fake.

That is just a down and dirty quick way of avoiding shadows on the back ground and it is vary fast for me. From the image I saw I thought that was what coran was trying to accomplish.
I'm sure there are better ways and you being the guru of the node world would know what to do.
As far as reflections go you are absolutely right. I do intend to play around with what you suggested.  But unless I am missing something I do not understand how your way would be fast.
I have followed several of your post here and find most vary enlightening and helpful. I for one thank you for all the effort and knowledge you have given to the community.
Now that I have sucked up totally, back to the point.
If I used the method you have suggested say with V4, hair ,hat ,clothes,jewelry and other props, would I not have to re-connect every image of every item in the setup?  V4 alone contains many images. What am I missing here?

If you ever published a tutorial on node manipulation and setup I for one would throw so money your way.   hint, hint, hint

I am rather a newbie at this so didn't understand all the node talk. Rather complicated me thinks. Need to look at this node thing some time but not now. I attach the same portion of the final render to show the difference.

My backgound was made up of a square object flat plane. The photo I used as the image was added through the material area of poser. My issue is that the image I used has a finite resolution to start with and if I increase its size too much, the pixels of the image will start to show and make that part of the final render rather pixelated. In moving the object back to stop the shadows I would have to increase the overall size of the object so the edges didn't become visible. Perhaps the only analogy I can think of here is of zooming. Zooming can only happen just so far before the pixelation appears. The balance is between zooming and pixelation and getting the render as good as possible.

The other suggestion to set the backgound not to cast shadows didn't seem to work. The shadows still appeared. Perhaps an option for an object 'not to accept shadows' would be a better description.

I have added this final render to my gallery under fantasy. Please have a look to see if I am going in the right direction with my work. It is called Surrender. As I said before, I am a newbie.

looks o.k. to me.  objs need rim lighting to show the fx of the apparent lite sources in bg IMVHO.

Quote - But unless I am missing something I do not understand how your way would be fast.
...
If I used the method you have suggested say with V4, hair ,hat ,clothes,jewelry and other props, would I not have to re-connect every image of every item in the setup?  V4 alone contains many images. What am I missing here?

There's no connecting of the image to those materials. We're talking about a single prop placed in the scene - a big rectangle. That's the only work you have to do. The OP was doing that already. And the OP simply needed to disconnect the ImageMap from one place and connect it in a different place, one that doesn't involve paying attention to lights.

That's all there is to it.

There is no additional work beyond what the OP had already done. The only difference is where to connect that Image_Map node. Connect it to Alternate_Diffuse and set Diffuse_Value = 0. Done.

Quote - > Quote - But unless I am missing something I do not understand how your way would be fast.

...
If I used the method you have suggested say with V4, hair ,hat ,clothes,jewelry and other props, would I not have to re-connect every image of every item in the setup?  V4 alone contains many images. What am I missing here?

There's no connecting of the image to those materials. We're talking about a single prop placed in the scene - a big rectangle. That's the only work you have to do. The OP was doing that already. And the OP simply needed to disconnect the ImageMap from one place and connect it in a different place, one that doesn't involve paying attention to lights.

That's all there is to it.

There is no additional work beyond what the OP had already done. The only difference is where to connect that Image_Map node. Connect it to Alternate_Diffuse and set Diffuse_Value = 0. Done.

A vary bright light just clicked on......        Thanks