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I produce a lot of basic "product on white" renderings for Amazon images. I have a few methods for getting to what I want, but most involve quite a bit of rendering multiple images and compositing via Photoshop, etc. I'm wondering if anyone can offer advice on their preferred workflow to get the best on white product images straight out of one render without having to edit. A couple things I'm looking for advice on acheiving:

  1. Pure white background (do you use a seamless and light it? or just use a white background? Any other tricks?)
  2. Minimal shadows - on Amazon, the container is a tightly cropped square, so dealing with shadows is an issue and you can't rely on those nice long, realistic shadows - I'm trying to determine how to get minimal shadows like the attached examples straight out of the gate with no editing. I realize the answer lies in lighting, but it seems that if I adjust the lighting to make the least amount of shadow, my subject's lighting suffers, and vise versa. Have you found any ways to control the shadows separately from the lighting of the object?

enter image description here

enter image description here

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    $\begingroup$ Pure white background is easy to achieve. Don't put any kind of floor under the product, in the Render Properties panel set Film > Transparent and in the Compositor you mix the rendered image with the Alpha Over Node over white colour. For the separate shadow I have to test something tomorrow, but I think there's a way, too. $\endgroup$ Nov 30 '20 at 22:20
  • $\begingroup$ Oh, of course if you want some floor reflecting light or anything on the product without being visible, select the floor, go to the Visibility settings and disable Camera. $\endgroup$ Nov 30 '20 at 22:50
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To achieve the desired result it's best to create two scenes: the first one for the product, the second for the shadow.

  1. The first scene contains the product and all lighting like lamps, HDRI environment etc. for lighting the product as it should look like. A floor maybe for light bounces or blocking light from below the product. Set Render Properties > Film > Transparent. Hide the floor from the camera by disabling Object Properties > Visibility > Ray Visibility > Camera.
  2. Create the second scene by copying the first one (a word on linked duplicates at the end of this answer). Make the floor visible again by enabling Ray Visibility > Camera and enable Visibility > Ray Visibility > Shadow Catcher. Delete all lamps, set World > Strength to 0.0, put a plane with Emission shader above the product and play with the settings until the shadow is correct. Now hide the product from the camera like you did with the floor in the other scene.

Scene setup

  1. Now both scenes are setup for rendering. In the Compositor, choose a Render Layer Node for the shadow scene and use an Alpha Over Node with a white colour to put the shadow on a white background. Add a second Render Layer Node for the product scene and place it above the shadowed background with another Alpha Over Node.

Compositing

  1. If you hit F12 now to render the image, both scenes will be rendered and composited together.

You can now maybe save the setup as a stage for other products. If you want to change something on the product or the floor without having to create the shadow scene again it's best to make those objects linked duplicates, so any changes will apply to both of them. It's important that they're not the same objects just linked to both scenes, otherwise they cannot have different viisibility settings.

A last side note on rendering with Color Management set to Filmic: because it has a much higher dynamic range, the 'normal' white with a brightness of 1 will usually be a light grey instead of pure white. To achieve pure white in Filmic the background white must have a brightness of around 16.19 - which means, the shadow seems to disappear. Considering you want to render with Filmic it would be the best only composite the shadow and product over a transparent background and add the white in another program like Photoshop, Gimp etc.

//Edit: I've uploaded a file where I show the things described in the comments.

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  • $\begingroup$ Thanks Gordon, really appreciate your detailed response -- one thing I'm a little confused on is the Emission shader plane - can you show me the setup for nodes for this? I have it in place but can't seem to figure out how to adjust the size/diffusion of the shadow?? $\endgroup$ Dec 21 '20 at 22:05
  • $\begingroup$ I'm also having trouble outputting the composite with a transparent background - can you clarify how I would do that in the node setup? As you say, the white background is not ideal for this but can't seem to figure it out with this setup - thanks again! $\endgroup$ Dec 21 '20 at 22:21
  • $\begingroup$ To output it on a transparent background you just plug the Render Layers node of the shadow scene directly into the first socket of the Alpha Over node and the product scene into the second socket, so you simply don't put it over white color at the beginning. Then save it as a PNG ot TIF set to RGBA. $\endgroup$ Dec 23 '20 at 7:12
  • $\begingroup$ For the shadow, here's a few tricks: since this scene only shows a shadow on the floor,, no object, no light etc., you can manipulate it in some ways. For example, if the shadow gets too large in diameter, try adjusting the size and height of the emission plane above it. Or even the strength. If your shadow gets to sharp, maybe blur it in the Compositor before the Alpha Over. The width of shadows not only depends on the relation of the light plane's size and height above object, but also the height of the object itself. Try putting the bottom half of the product on the floor for example. $\endgroup$ Dec 23 '20 at 7:26
  • $\begingroup$ Cutting off the top the product can also be done non-destrucive by using a Boolean Modifier. I'll take a cube, set it to Intersect and choose the product in the Object selection. I'll edit my answer and attach a file where I do all those tricks. $\endgroup$ Dec 23 '20 at 7:32

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