Can't make object ignore shadows.

[Anonymous]

Hi,

I'm trying to render a scene with several 3d objects. I want one of these objects NOT to cast a shadow. I go to properties,select the object and under 'shadow disply' select 'ignore shadows'. In the viewport the shadow disappears from the object. However, when I render the shadow reappears.

Any ideas why this might be happening?

[wispoxy]

To Work With Backgrounds and Shadows

Jun 25 2015  |  In-Product View

Applies to AutoCAD 2016, AutoCAD Architecture 2016, AutoCAD Civil 3D 2016, AutoCAD Electrical 2016, AutoCAD MEP 2016, AutoCAD Map 3D 2016, AutoCAD Mechanical 2016, AutoCAD P&ID 2016, AutoCAD Plant 3D 2016, AutoCAD Structural Detailing 2016, and AutoCAD Utility Design 2016

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Specify solid, gradient, image, sun/sky, or image-based lighting (IBL) maps as the background to model space or a viewports.

Control the Display of Shadows

1. In the viewport, upper-left corner, click the Visual Style Controls and Visual Styles Manager.
2. Alternatively, click View tab Palettes panel (expanded) Visual Styles  Find or Visualize tab Visual Styles panel Dialog box launcher
3. In the Visual Styles Manager, select a visual style other than 2D Wireframe.
4. Under the Lighting category, enable Highlight Intensity and set the following properties: Highlight IntensityShadow Display

Display the View Manager to Set a Background

1. In the viewport, upper-left corner, click the View Controls and View Manager.
2. Alternatively, click View tab Views panel View Manager or Visualize tab Views panel View Manager. Find
3. In the View Manager, click the name of the view you want to modify. If the view is not displayed, expand the appropriate node in Views list.

Set a Solid Viewport Background

1. In the View Manager, Properties panel, under General category, click the Background Override field and select Solid.
2. In the Background dialog box, under the Solid Options section, click the Color swatch.
3. In the Select Color dialog box, specify the color you want to use for the background and click OK.
4. In the Background dialog box, click OK to return to the View Manager.
5. In the View Manager, click Set Current and then click OK.

Set a Gradient Viewport Background

1. In the View Manager, Properties panel, under General category, click the Background Override field and select Gradient.
2. In the Background dialog box, under the Gradient Options section, specify the desired options for the gradient fill.
   • Check Three Color to create a three color gradient background.
   • Click on each color swatch to display the Select Color dialog box and specify the color you want to use.
   • Enter a rotation value for the gradient fill in the Rotation text box.
3. In the Background dialog box, click OK to return to the View Manager.
4. In the View Manager, click Set Current and then click OK.

Set an Image as a Viewport Background

1. In the View Manager, Properties panel, under General category, click the Background Override field and select Image.
2. In the Background dialog box, under the Image Options section, click Browse and specify the image for the background. Click Open.
3. Click Adjust Image.
4. In the Adjust Background Image dialog box, specify the desired options for the image and click OK.
   • Specify the position for the image by choosing an option from the Image Position drop-down list.
   • Click Offset or Scale to adjust what functionality the sliders have.
   • Check Maintain Aspect Ratio When Scaling to have the image scale uniformly.
   • Drag the sliders to adjust the offset or scale of the image based on the current setting.
5. In the Background dialog box, click OK to return to the View Manager.
6. In the View Manager, click Set Current and then click OK.

Enable the Sun/Sky as a Viewport Background

Before changing the background, make sure that photometric lighting is enabled.

• Click Visualize tab Lights panel (expanded) Lighting Units drop-down American Lighting Units

Find or International Lighting Units

• Find.

  Photometric lighting is enabled, and American or International lighting units is set.

After photometric lighting has been enabled, you can enable the Sun/Sky and specify the desired settings.

1. Display the View Manager.
2. In the View Manager, Properties panel, under General category, click the Background Override field and select Sun & Sky.
3. In the Adjust Sun & Sky Background dialog box, specify the desired options for the background and click OK.
4. Click OK to return to the View Manager.
5. In the View Manager, click Set Current and then click OK.

Set an Image-based Lighting Map as a Viewport Background

1. Display the View Manager.
2. In the View Manager, select an existing view or create a new view.
3. Click Set Current and then click OK.
4. Click Visualize tab Render panel (expanded) Environment > Find
5. On the Render Environment & Exposure palette, click the Environment toggle to enable image-based lighting.
6. Click the Image Based Lighting drop-down list and select an image.
7. Select the Use IBL Image as Background option.
8. Optionally, drag the Rotation slider or enter a value in the Rotation text box to adjust the rotation of the image.

Related Concepts

• About Backgrounds and Shadows
• About Shading, Highlighting and Coloring Faces
• About Controlling the Display of Edges

Related Reference

• Commands for Model Shading, Edge Effects, and Visual Effect Performance

[jggerth]

sounds like a job for post-processing.  Render the scene with ony that object, and a monochrome (green screen) background, and render the scene with everything else as you want it.  in a photo editor, paste in the single object no shadow render as a new layer, over your full image, and set the greenscreen transparent.

[Anonymous]

Thanks for reply. I could try that but it sounds complicated as I would have to render the green screen scene in exactly the same position as the main render. Everything looks like it should be possible to do it all in autocad and it works in the viewport, just not in the render. Is it a bug or am I perhaps missing something?

[dgorsman]

You don't *necessarily* need to render with a CSO (color separation overlay) background as long as you can render the file with a functioning alpha channel.  Then you render the object with no background and the image includes the mask.  Still requires compositing.

As for doing this right out of the software... this sounds like a job for Superm er proper visualization software.  😄

[wispoxy]

In the Visual Styles Manager, select a visual style other than 2D Wireframe.

[Anonymous]

Many thanks for trying to help but I'm not entirely sure what you mean. I can get the shadow not to show in the viewport but it always reappears when rendering. I've tried various styles in the viewport but nothing works.

[Anonymous]

Thanks. That sounds a bit beyond my capabilities at the moment. maybe should have used Rhino or something but it's modelled in Autocad now. Will persevere.

[Anonymous]

---

@Anonymous wrote:
In the Visual Styles Manager, select a visual style other than 2D Wireframe.

---

wisp, you do realize there is a difference between view style and actual rendering don't you?

[wispoxy]

Yes, because you can view 2D Wireframe in rendering also.

[jggerth]

can you post a sample drawing?  cut it down to one object that you don't want to throw shadows, and a couple that do throw shadows,

[Anonymous]

Sure, I'll attach a low res render and the autocad file. In the render you will see yellow tapes. These ae the objects which I don't want to cast shadows. Everything else should cast shadows.

[Anonymous]

Sorry, attached the render twice in the last post. The autocad file is too big. I'll reduce it and try again.

[Anonymous]

Here's the reduced autocad file.

[dbroad]

Andy,

You have brought out a good point.  There should be some control over the linkage between the visual styles settings regarding shadows and the rendering results.  If you have 3DS Max, you can better control your render results by importing your cad drawing.  Otherwise post processing by overlaying the renderings with and without the shadow ignoring and shadow casting objects in photoshop layers as suggested earlier is the only workaround I know of.

This might be worth proposing as either a bug fix or a feature request depending on how you view the current situation.

[Anonymous]

Many thanks for looking at it anyway. So I guess it's just a frustrating Autocad bug? - been trying to work it out for hours! I don't have 3dsMax but I could possibly find someone who does. Alternatively, I'll do it in Photoshop or Illustrator as you said. Thanks again.

[Alfred.NESWADBA]

Hi,

>> when I render the shadow reappears.

You are using AutoCAD 2016, am I right?

Because AutoCAD 2015 does the shadow handling correct, setting the object to "Receives shadows" or "Ignore shadows" (in property window, property "Shadow display" while the object is selected) does not show the shadows.

The settings "Casts and Receives shadows" as well as "Casts shadows" let the object create shadows.

I have added to your drawing 4 cylinders with the 4 shadow display settings (left cylinder first setting, second cylinder second shadow setting, ...)

And this is the result from AutoCAD 2015 (shadows as you like):

That screenshot is a render-result from AutoCAD 2016:

>> So I guess it's just a frustrating Autocad bug?

Seems so, create a support ticket and show them (Autodesk) this drawing and the bug, helpfully for them would be if you provide a link to this thread here.

For now, if you have a subscription, you can install up to 3 releases back, so if that is a daily need, go back to 2015 for your rendering projects.

At least this is something which has it's origin in "realistic rendering" as none-transparent materials in the real world do cast shadows 😉

- alfred -

[wispoxy]

What AutoCAD version and OS Version / Graphics / Ram?

If you're using AutoCAD 2016 and Window's 10 together, you're just asking for problems because they are both new and filled with glitches.

[dbroad]

Thanks for posting that Alfred.  Those pics put the lack of functionality in 2016 squarely in bug territory.

[Alfred.NESWADBA]

Hi,

new info I got yesterday ... try in AutoCAD 2016 to set the (none documented) systemvariable RENDERENGINE to 0, looks like that makes again MentalRay active.

Looking to find something about that variable I found an article describing your issue >>>here<<<.

Besides of that I have found >>>this article<<< describing differences of the old and current render engine.

- alfred -