What would cause DOF to fail?

[Boofredlay]

I was trying a DOF render and it was jut not focusing correctly.
It would be sharp off in the distance but what I set as the camera
target (then saved the scene) was way out of focus.
So as a test I copied everything to a new file and set up the DOF
exactly the same way and it is working fine now. So, what might
cause a DOF to fail? Other than operator error.
And yes I read the manual.

[Fletch]

It's catching on?! (reading the manual)

well, it's possible, if you hit a scene tab, and then hit 'render' while SU is stil transitioning to the scene tab, that it will find a focus point that is quite eratically different from the one you expect.

it could be the person is accidentally forgetting to set F-number (been there, done that)

I'm guessing neither of those was the case with you, but... there may be others...

glad to hear it's working properly.

[Chris]

The "target" for the DOF is the Sketchup camera's target. Camera target is one of the elements that is interpolated with different scene pages (like camera position, shadows, layer visibility etc). So if you set the target, if you have scenes, you need to make sure you do an "Update" on the appropriate scene, or you'll loose the target position.

As Fletch describes, there can be a weird error that occurs if you try to render while SU is transitioning from one scene to the next. But more likely the problem is that the target is getting reset do to the scene tabs.

[Boofredlay]

Well I think I did everything correctly, updating, not rendering in scene transition etc.. but one never knows.
Thanks for the replies guys.

[Boofredlay]

Ok, so I have the new TR build installed and am testing DOF but I am not getting it to work properly.
I click the "Position the scene's view" button, hold Ctrl and click the center of an object in my scene. I change the F number to 1 for an exaggerated DOF and hit render. No DOF. So I repeat the steps then create a scene, no DOF.

What am I doing incorrectly? Am I missing a step?

This model was created on my home machine from scratch after the new TR build was installed. I say this because I have had troubles in the past building a scene on another computer then bringing it to this one to render.

Thanks for any insight.

[Chris]

It sounds like you are doing everything correctly. What is your Lens Focal Length? This can make a huge difference in DOF. I'm not a professional photographer, but I believe that it's not uncommon to have focal lengths of 100mm or more when creating a DOF effect in a photo. A lot of that depends on your scene scale as well. I find, for a given focal length, a very small scene produces much stronger DOF than a large scene. Here, the small scene is about 1/10th the physical size of the large scene. The large scene is about 6' across the horizontal.

F-1, 200mm focal length

small_f1_200mm.jpg (108.91 KiB) Viewed 9583 times

large_f1_200mm.jpg (107.11 KiB) Viewed 9584 times

a lot depends, too, on your scene composition. If all your scene elements are at an equal distance from the view point, you won't see any, or much DOF. Not compared to a scene where their are near and far elements

[Boofredlay]

Thanks Chris.

The model is over 400' in length. The focal length is unchanged (39.645). Changing it to 200 really obscures the view. It changes the SU Field of View from 35 to 7, this is significant and not what I want to see.

I have since reduced the model to 25' in length and I am getting some results. So does this mean if you have a really large model that DOF is not achievable?

[Ecuadorian]

With such an extremely large model the only way to show the out-of-focus effect ("DOF" as you call it) is to focus on an object that is close to the camera, just like in the real world. Try setting the focus distance on something at a distance of 10'.

As Chris pointed out, having a shallow depth is more a characteristic of small models, like cardboard architectural models. This is so much the case, than when photographers pursue the same effect for large scale scenes the technique is called "miniature faking", and is normally achieved in Photoshop or with a special set of camera lens called "tilt-shift lens". These lens can be expensive and you also need an SLR to use them.

As in SketchUp you are a god with full control over your created world, there's no need to buy special cameras and lenses to do your "miniature faking": Just scale your whole model to make it a "real" miniature and shoot away your pictures.

[Fletch]

Eric, can you please provide the test scene? It sounds like it's a small file in size of kb?

[Chris]

If all else fails, you can always try post production DOF. With that, you can force a DOF that you would not normally ever be able to achieve. I've done it a few times with a gimp plugin specially for that purpose. I don't have any of the info right at hand, but I'll look around. I'm sure others have good links for that kind of thing.