Autocad Render to Window output is inconsistent if the viewport changes

[kchong78]

Hi All,

I wonder if I'm doing something wrong or if this is a bug in Autocad.

I have created a scene with solids, a camera and lights. When I have only 1 viewport (viewport control set to maximize) and have set the view controls to the created camera view, the render output is different compared to when I have multiple viewports. 

Why is this happening? Shouldn't the output all be exactly the same as a camera has been defined and the rendering be being created off the camera?

[Alfred.NESWADBA]

Hi,

>> the render output is different compared to

>> when I have multiple viewports

We don't see your display, "different" can be soo much (different color, shadow, materials, camera location, camera direction, camera view width/height, ...)

Would you mind sharing screenshots of what you see in AutoCAD and what you see in render window?

And with these screenshots please describe the difference to what you expect.

Also great to know:

• version of AutoCAD you are using (command _ABOUT ==> screenshot)
• uploading the dwg-file so we can try on our systems

- alfred -

[kchong78]

Hi Alfred,

Thank you for your reply.

The perspective of the render output changes ever-so-slightly when the size of the viewport changes. The materials lighting and everything else don't, but the perspective does, which leads me to think that a render created by Autocad doesn't really use the camera.

The images I have is not the best example but once you have objects closer to the camera, the difference in perspective becomes really noticeable.

Product Version: 23.0.61.0 AutoCAD Mechanical 2019.0.1

Built on: P.162.0.0 AutoCAD 2019.1.2

[Alfred.NESWADBA · Accepted solution]

Hi,

ok, your source of the issue is aspect ratio, which means the relation width to height of view.

As a simple example, when you have a window in CAD that is 1000x1000 pixel and you want to render this to 2000x500 the renderer can't show the same content in CAD as in the render window. It does that as good as possible, but there might appear differences as you notice.

I prefer to solve this in a layout I only use for rendering views/cameras:

• create a layout
• create a viewport, that has a X:Y relation that corresponds with the render-size/aspect ratio
• for every camera or every render resolution create one viewport and then, to start render, activate that viewport and render to your render window

Hope that is easy to understand and to follow, - alfred -

[kchong78]

Hi Alfred,

Thanks for your reply. I think your suggestion might solve my problems. I've not considered creating viewports in the layouts tab specifically for rendering before.

Regards.