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How do you do this: Cast Shadows on 2D background

ScavengerScavenger Posts: 2,674
edited December 1969 in The Commons

I was looking at an old v3 product and noticed something..

The product is a bunch of 2d backgrounds and poses...but the promo shows a figure casting shadow on the 2d background, not as if it was a wall (so the shadow would be vertical) but as if the character was actually standing on it (so the shadow is horizontal).

How would that be done? I've seen a lot of "background" products uses like this, as a setting for 3d characters.

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Comments

  • HavosHavos Posts: 5,404
    edited June 2015

    Scavenger said:
    I was looking at an old v3 product and noticed something..

    The product is a bunch of 2d backgrounds and poses...but the promo shows a figure casting shadow on the 2d background, not as if it was a wall (so the shadow would be vertical) but as if the character was actually standing on it (so the shadow is horizontal).

    How would that be done? I've seen a lot of "background" products uses like this, as a setting for 3d characters.

    I think this could be done with post work quite easily. Basically the steps are:

    1) Render the character with a blue floor so that shadow falls onto the floor.
    2) Bring into photo editor that supports layers (eg: gimp or PS)
    3) Select all with blue color and delete the rendered floor (the deleted area would become transparent)
    4) Select the shadow and make 50% transparent.
    5) Add in the background photo and move the figure layer around until it looks natural.

    Post edited by Havos on
  • Richard HaseltineRichard Haseltine Posts: 102,858
    edited December 1969

    Possibly postwork, possibly a shadow catcher on a primitive positioned to line up with the background object.

  • HavosHavos Posts: 5,404
    edited December 1969

    Richard Haseltine said:
    Possibly postwork, possibly a shadow catcher on a primitive positioned to line up with the background object.

    I don't think rendering the background image placed on a flat primitive would work, the image is just a jpg, not a HDR. You would need to place the primitive roughly horizontal and the background part of the image would thus be too low. Also the rendering process may significantly change the look of the photo.

  • ScytharScythar Posts: 127
    edited December 1969

    In the old days there was PW Catch (PoseWorks), but that doesnt work in the feb latest version of DS anymore.

  • ScavengerScavenger Posts: 2,674
    edited December 1969

    Havos said:

    I think this could be done with post work quite easily. Basically the steps are:

    1) Render the character with a blue floor so that shadow falls onto the floor.
    2) Bring into photo editor that supports layers (eg: gimp or PS)
    3) Select all with blue color and delete the rendered floor (the deleted area would become transparent)
    4) Select the shadow and make 50% transparent.
    5) Add in the background photo and move the figure layer around until it looks natural.

    1) I feel stupid that I didn't think "Photoshop", as it's my main graphics program that I use for everything. I mean REALLY STUPID.

    2) Wouldn't your step 3 pretty much take out the shadow too, unless the tolerance is set reallllllllllly low, in which case I'm not sure how the shadow would look.

    3) I could see a Shadow Catcher as a floor at the correct angle, then just mask off where it extends beyond the ice block (in this case)

  • ScavengerScavenger Posts: 2,674
    edited December 1969

    Scythar said:
    In the old days there was PW Catch (PoseWorks), but that doesnt work in the feb latest version of DS anymore.

    In 4.8? I'm sure I used it in 4.7....or maybe it was another thing I used.

  • HavosHavos Posts: 5,404
    edited December 1969

    Scavenger said:
    Havos said:

    I think this could be done with post work quite easily. Basically the steps are:

    1) Render the character with a blue floor so that shadow falls onto the floor.
    2) Bring into photo editor that supports layers (eg: gimp or PS)
    3) Select all with blue color and delete the rendered floor (the deleted area would become transparent)
    4) Select the shadow and make 50% transparent.
    5) Add in the background photo and move the figure layer around until it looks natural.

    1) I feel stupid that I didn't think "Photoshop", as it's my main graphics program that I use for everything. I mean REALLY STUPID.

    2) Wouldn't your step 3 pretty much take out the shadow too, unless the tolerance is set reallllllllllly low, in which case I'm not sure how the shadow would look.

    3) I could see a Shadow Catcher as a floor at the correct angle, then just mask off where it extends beyond the ice block (in this case)

    Gimp and photoshop have magic selectors to select around shapes, and as long as the shadow was reasonably sharp I think it would be possible. However thinking about it the floor would need to be grey not blue, or your left with a bluish shadow. If the edges of the shadow are made a bit more transparent than the rest it should blend in. It is not trivial now I think about it, but still doable.

  • Peter FulfordPeter Fulford Posts: 1,325
    edited December 1969

    Scavenger said:
    The product is a bunch of 2d backgrounds and poses...but the promo shows a figure casting shadow on the 2d background, not as if it was a wall (so the shadow would be vertical) but as if the character was actually standing on it (so the shadow is horizontal).

    The backgrounds in this particular product appear to be of 3D scenery, presumably made by the vendor. In which case the vendor may have simply rendered the V3 model in the 3D scene for the promo pic.

    .

  • RenpatsuRenpatsu Posts: 828
    edited December 1969

    Havos said:
    Richard Haseltine said:
    Possibly postwork, possibly a shadow catcher on a primitive positioned to line up with the background object.

    I don't think rendering the background image placed on a flat primitive would work, the image is just a jpg, not a HDR. You would need to place the primitive roughly horizontal and the background part of the image would thus be too low. Also the rendering process may significantly change the look of the photo.

    Richard does not mean "rendering the background image placed on a flat primitive", he is talking about a primitive with a shadow catcher that is placed similarly like the 3D object in the background image appears to be (e.g. the ice cube). So the primitive only catches the shadows and has got nothing to do with the background image rendering itself.

  • CypherFOXCypherFOX Posts: 3,401
    edited December 1969

    Greetings,
    In Iray this can be done with a 'matte object'. That is, an object that exists in-scene, but isn't rendered. It still manages things like shadow-catching, light-catching, reflections, and more, but the object itself doesn't get rendered, just its interactions with the environment.

    It's kind of awesome. :)

    -- Morgan

  • millighostmillighost Posts: 261
    edited December 1969

    Scavenger said:
    Scythar said:
    In the old days there was PW Catch (PoseWorks), but that doesnt work in the feb latest version of DS anymore.

    In 4.8? I'm sure I used it in 4.7....or maybe it was another thing I used.
    Can also be done with ShaderMixer. I do not know the PWCatch, or what if it does anything different. But ShaderMIxer still works in 4.8.

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