Distace from Camera to object in drawing.

[Al Hart]

I would like to be able to move the mouse around on a drawing and view the distance from the camera to the object near the mouse.

I know I could write a tool to do this, but there is probably one out there already. Can someone point me in the right direction?

[Gaieus]

Hi Al,

Here is one - by Rick - and it's free!
http://www.smustard.com/script/CameraDistance

[Jim]

Maybe Fullmer (or you) can add this to his Onscreen plugin:

viewtopic.php?f=323&t=16837

[Al Hart]

Hi Al,

Here is one - by Rick - and it's free!
http://www.smustard.com/script/CameraDistance

Thanks, I'll give it a look.

[Chris Fullmer]

Maybe Fullmer (or you) can add this to his Onscreen plugin:

viewtopic.php?f=323&t=16837

Oh Jim, that is an old plugin. I should look at it again. i can't believe it works at all!

Chris

[Jim]

Oh sorry - I know how you feel!

[Al Hart]

Hi Al,

Here is one - by Rick - and it's free!
http://www.smustard.com/script/CameraDistance

This one returns to distance from the camera t the eye.

I would like to have a tool which lets you determine the distance from the camera to arbitrary objects in the drawing. I want to use it to set Focal Lengths for Depth of Field calculations.

This is not a good example, because the eye may be in the same place as the center of focus, but if the eye were raised up a bit, then it would probably be way behind the desired focal point.

[thomthom]

Ah - yes. That would be a good tool. And for my use, since I'd use V-Ray I'd want it to display the distance in inches as well as model units.

Not sure if there's a tool like that out there though.

[TIG]

Assuming that you have something selected then

Code: Select all

model=Sketchup.active_model
eye=model.active_view.camera.eye
ss=model.selection[0]
distance=eye.distance(ss.bounds.center)

returns the distance from the camera's 'eye' to the 'center' of the selection's bounding-box...
You can of course improve this - another way to get the distance to the 'face' of a selection would be to get the vector between the 'eye' and the 'center' and then do a 'raytest' to find the first point hit and get that distance...

Code: Select all

model=Sketchup.active_model
eye=model.active_view.camera.eye
ss=model.selection[0]
distance=(model.raytest[eye, eye.vector_to(ss.bounds.center)])[0].distance(eye)


This then returns the 'distance'...
You can improve it further by testing if the second item in the returned raytest array contains the selected object and if not redo the raytest from the first item [point] in its array along the same vector...

Code: Select all

model=Sketchup.active_model
eye=model.active_view.camera.eye
ss=model.selection[0]
vector=eye.vector_to(ss.bounds.center)
rayt=model.raytest[eye,vector]
pt=rayt[0]
while not rayt[1].include?(ss)
  rayt=model.raytest[pt,vector]
  pt=rayt[0]
end#while
pt=rayt[0]
distance=eye.distance(pt)


Hope this helps...

[Al Hart]

I took the utilitiestools.rb script in SketchUp, which displays an X,Y location as you move the mouse and changed it to display the distance from the camera instead.

get_focal_length.jpg

The heart of the change is this routine to display the camera distance:

Code: Select all

   # get camera distance from the eye to a point at (x,y,0)
   def get_distance(target)
      model = Sketchup.active_model
      eye = model.active_view.camera.eye
      distance = eye.distance(target)
      # display in drawing units and inches
      slength = Sketchup.format_length(distance) + sprintf(" (%g\")", distance)
      return slength
   end#def


Try the attached script: get_camera_distance.rb

[Edit: I uploaded a new version of get_camera_distance.rb]

[TIG]

But that measures the eye to target distance...
You want the eye to object distance ?
The object might be between the target and the eye positions !
See my example on how to use the eye>>>target vector and raytest from the eye along that vector for objects in between... perhaps using a selected object as the source [it needs work as it was only a first draft... but selecting a group/instance between the eye and target will give the distance to it ?]

[Al Hart]

There was a bug in get_camera_distance.rb.

I uploaded a new version.

(One person had downloaded it already - sorry - please get a new version)

[Al Hart]

But that measures the eye to target distance...
You want the eye to object distance ?
The object might be between the target and the eye positions !
See my example on how to use the eye>>>target vector and raytest from the eye along that vector for objects in between... perhaps using a selected object as the source [it needs work as it was only a first draft... but selecting a group/instance between the eye and target will give the distance to it ?]

I call get_distance(target) with the point from OnMouseMove() after calling pick(x,y) - not the target of the camera view.

I think it is working properly.

Here is a rendering after selecting the end of the cylinder as the target point and setting the Depth of Field to be very blurry (3.0).

focal_length.jpg

[TIG]

I apologize...
I hadn't read your script fully - your target isn't camera.target - you have a good idea - it works fine...

[Bertier]

hello

could that plugin be used to create motion blur in an animation ?

thank you.

[mpowell1234567890]

Cool, thanks. Love it when I can know how far away something is in a model.

I took the utilitiestools.rb script in SketchUp, which displays an X,Y location as you move the mouse and changed it to display the distance from the camera instead.

get_focal_length.jpg

The heart of the change is this routine to display the camera distance:

Code: Select all

   # get camera distance from the eye to a point at (x,y,0)
   def get_distance(target)
      model = Sketchup.active_model
      eye = model.active_view.camera.eye
      distance = eye.distance(target)
      # display in drawing units and inches
      slength = Sketchup.format_length(distance) + sprintf(" (%g\")", distance)
      return slength
   end#def


Try the attached script: get_camera_distance.rb

[Edit: I uploaded a new version of get_camera_distance.rb]

[pibuz]

That is a lovely script, but it seems I'm not able to load it..
How can I do that?

Thanks a lot Al!

**EDIT: ok, I moved the original utilities rb to another folder and renamed your script "utilitiestools.rb", and it works: now I can get camera distance
Is there a less homemade or brute method? Thanks again?

[Dan Rathbun]

Renaming files is dangerous.

Make a subfolder of Plugins dir, named: !_autoload

"Plugins/!_autoload"

Then get my !autoload script here, and put it in Plugins folder.

After.. you can put little scripts that you wish to autoload in the "Plugins/!_autoload" folder.

[angeli7on]

Hi, I got confused about this.
I try using get_camera_distance but the result aren't DOF
am I missing something ?

here I attach my screen shot
if too small I also upload here:
http://imageshack.us/f/254/bingungdof2.jpg

please advice, thanks alot.

[TIG]

But the distance given by the tool is 703" - not '10' units in the Camera DOF dialog ?
Try using the real equivalent distance [in the correct units for that dialog] to see what happens.
The distance returned by the tool is the distance from the camera 'eye' up to the picked point - in your screenshot it's given in 'inches'...

[Chris Fullmer]

Yeah, so what are the expected units of that rendering dialog box? Feet? Meters? cm?

703 inches =

58.58 feet
17.8562 meters
1785.62 cm

My best guess is that it is expecting feet or meters based on the DOF shown in the 2 screenshots. 10 is too close, but 703 is clearly waaaaaaay to far. So its gotta be something in the middle, which would probably be feet or meters.

[angeli7on]

Hi TIG and Chris Fullmer, thanks for your reply.
I think I already put the unit into inch. and I already put 703 (not just 10) in Overide_focal_dist, but the result are all sharp.
I got 703 from get_camera_distance plugin, on the red ball.
here I attach another screenshot with color and setting, I'm going to make the red ball to be sharp and the other ball become blurry.
Do you have simple samples of your blurred .skp ?
and here also my .skp file in google drive:
https://docs.google.com/open?id=0BxjFhe ... VFKdFNWRHM
many thanks for your help guys.

[Chris Fullmer]

It's unclear if you tried what we suggested. I told you to try 58.8 in case V-Ray is expecting the input to be in feet, or put 17.8562 in case it is expecting meters. Do those two numbers then report back.

[Chris Fullmer]

To elaborate again, the SketchUp pop-up is saying 703". But it appears that the V-Ray window is expecting the input to be in something other than inches, otherwise it would have worked. So other common units would be feet or meters. Since we know that object is 703" from the camera, we'll convert that to feet. It is 58.8 feet. Or maybe V-Ray is expecting meters, so convert 703" to meters and you get 17.8562 meters. That is why I'm saying try those two numbers, I'm hoping one will work. Then you will know from that point on, which unit V-Ray is expecting.

[thomthom]

Have you tried adjusting the F-Stop?

[Chris Fullmer]

Looks like he's got his f-stop set at 2.8. That should give a good DOF blur. And indeed in his first post, the image where he has f-stop at 2.8 and focal distance at 703, there is no visible blur, but when he changed the focal distance to 10, the entire image was blurry, indicating that the DOF is working, he just needs to set the correct distance.

[Chris Fullmer]

I'm already changing my mind. I can see that lowering the f-stop even more might be needed Thom, good call. That should definitely be tried as well.

The further the object is, the harder it is to get a shallow DOF (blur). Lowering the aperture will help create even more blur. But its possible the object could be so far away that there will never be any apparent blur. You could resort to using tilt frame to force a blur. But I'm thinking at that distance, you should be able to get some blur.

[thomthom]

He used a tool to measure the distance, so it should be correct.
It is possible that the F-Stop in VfS isn't working 100% like a real camera does.

[Chris Fullmer]

Well, in thinking about it, he's trying to blur something that is 58 feet or 17+ meters away. I'll get out my camera later today and open it to 2.8 and shoot something at about that distance, see if it produces any blur. At that distance, there is a chance there should be no blur.

[TIG]

As I understand it... the bigger the f-stop number the greater the depth of field about the focal-depth.
So a large number uses a 'pinhole' which has almost everything focused about that point, but a small number uses a 'wide-eyed' aperture which focuses on the point, with things nearer or farther away being shown blurred...
In real cameras the smaller the aperture size [i.e. the bigger the number] the less light gets into the 'film' and so this affects the shutter-speed in turn - so then there are three variables to juggle. But in rendering the focal-depth and f-stop interact to control the sharpness of objects that are nearer/farther away... and the 'speed' is therefore somewhat arbitrary...