Multimode helium–neon lasers have a typical coherence length on the order of centimeters, while the coherence length of longitudinally single-mode lasers can exceed 1 km. Semiconductor lasers can reach some 100 m, but small, inexpensive semiconductor lasers have shorter lengths, with one source[4] claiming 20 cm. Singlemode fiber lasers with linewidths of a few kHz can have coherence lengths exceeding 100 km. Similar coherence lengths can be reached with optical frequency combs due to the narrow linewidth of each tooth. Non-zero visibility is present only for short intervals of pulses repeated after cavity length distances up to this long coherence length.

HI jimhami42, I have a number of scenes displayed like your example and clipping is occurring in a couple of scenes. I am using Sketchup pro 2015. In trying to use your example: Go to scene manager highlight all scenes, uncheck camera location box, highlight one scene with an iso scene where the camera is set to perspective, and change FOV. I update only that scene with the camera location box not checked. I highlight all scenes and check the camera location box. Now all my scenes are from the same iso camera location (rather than front side top etc.)

Diagonal field of viewto horizontal

Do any of you know why we jump from 35 deg to 30 deg between pro and make versions? does this also has to do with advanced camera tool?

Make sure you are in “Perspective” mode for the camera when you save or update your scene. The field of view only has relevance with perspective views.

Horizontal vsdiagonal field of view

I believe these two are default value of SketchUp 2015 Pro. In Clipping & missing faces - http://help.sketchup.com/en/article/36261 states that “One is when the field of view (FOV) is set very wide. You can adjust the FOV between 1 and 120 degrees (the default is 35 degrees in SketchUp and 30 degrees in SketchUp Pro).”

BTW, 35mm film uses a 3:2 aspect ratio. All 35mm camera lenses reference this, so the diagonal is just as good as either vertical or horizontal. However, this underlying use assumes the 3:2 aspect which, while close to the Golden Mean, is rarely encountered in the video monitor world.

FOV calculator

The trick with the “Camera position” was in response to your question about setting all the FOVs at once. This also reset the camera position (or viewpoints) for all the frames.

Viewangle

Open your first scene and set everything the way you want it (including perspective, clipping, shading, layers, FOV, etc.) and then right-click that scene tab and click “Update”. When you come back to it, it should be the same. Now click on your second scene tab and repeat these steps. Loop through each tab until done.

Tolansky's An introduction to Interferometry has a chapter on sources which quotes a line width of around 0.052 angstroms for each of the Sodium D lines in an uncooled low-pressure sodium lamp, corresponding to a coherence length of around 67 mm for each line by itself.[5] Cooling the low pressure sodium discharge to liquid nitrogen temperatures increases the individual D line coherence length by a factor of 6. A very narrow-band interference filter would be required to isolate an individual D line.

If your scene manager is set to retain the camera (i.e., “Properties to be saved Camera location” is checked), it will store the settings with the scene. However, if you make any changes to a scene at all, make sure to right-click the scene tab and update the changes. Otherwise, they will revert to the scene creation settings or last update made.

HI Jimhami42, thanks for responding. On my scenes I want to have the camera on Parallel projection to get front, side and top elevations in Layout. If I go to Perspective or 2 Point Perspective I get the 3d view and not the standard drafting layouts. I cannot then make the FOV changes in any scene (since it is not available). Perhaps I am missing something here.

The coherence length can also be measured using a Michelson interferometer and is the optical path length difference of a self-interfering laser beam which corresponds to 1 e ≈ 37 % {\displaystyle \,{\frac {1}{\,e\,}}\approx 37\%\,} fringe visibility,[3] where the fringe visibility is defined as

The easiest way I know how to do so is to open the Scene Manager and highlight all of the scenes. Then uncheck the “Camera location” box and make the FOV settings in the first scene. Click update and then go back to the scene manager. Highlight the scenes and check the “Camera location” box … that should reset all subsequent scenes to the currently displayed settings.

In physics, coherence length is the propagation distance over which a coherent wave (e.g. an electromagnetic wave) maintains a specified degree of coherence. Wave interference is strong when the paths taken by all of the interfering waves differ by less than the coherence length. A wave with a longer coherence length is closer to a perfect sinusoidal wave. Coherence length is important in holography and telecommunications engineering.

In optical communications and optical coherence tomography (OCT), assuming that the source has a Gaussian emission spectrum, the roundtrip coherence length L {\displaystyle \,L\,} is given by

Diagonal field of viewcalculator

In long-distance transmission systems, the coherence length may be reduced by propagation factors such as dispersion, scattering, and diffraction.

where λ {\displaystyle \,\lambda \,} is the central wavelength of the source, n g {\displaystyle n_{g}} is the group refractive index of the medium, and Δ λ {\displaystyle \,\mathrm {\Delta } \lambda \,} is the (FWHM) spectral width of the source. If the source has a Gaussian spectrum with FWHM spectral width Δ λ {\displaystyle \mathrm {\Delta } \lambda } , then a path offset of ± L {\displaystyle \,\pm L\,} will reduce the fringe visibility to 50%. It is important to note that this is a roundtrip coherence length — this definition is applied in applications like OCT where the light traverses the measured displacement twice (as in a Michelson interferometer). In transmissive applications, such as with a Mach–Zehnder interferometer, the light traverses the displacement only once, and the coherence length is effectively doubled.

DiagonalFOV to horizontal and vertical

[edited] BTW, 35mm film uses a 3:2 aspect ratio. All 35mm camera lenses reference this, so the diagonal is just as good as either vertical or horizontal. However, this underlying use assumes the 3:2 aspect which, while close to the Golden Mean, is rarely encountered in the video monitor world.

I have noticed that I can type “35mm” or “35 deg” in field of view VCB. I also have noticed that SketchUp seems to remember what unit that I have used for the last time. Therefore, it shows 57mm as default field of view, but if i use “deg” unit and restart sketchup, it would display “35.00 deg.”

The nominal diagonal angle of view is defined as the angle formed by imaginary lines connecting the lens second principal point with both ends of the image diagonal.

Horizontal FOV calculator

If you want all the views laid out at once like you might see on a blueprint, then create multiple copies of the geometry and place them in one view:

To simplify matters let’s say on the model you sent that I want to change the FOV on all the scenes you created. They are presently at 25 degrees. In this case I want to make them all 35 deg. The scenes 1 through 4 have the camera at parallel projection and have the FOV embedded at 25 deg. I want to retain the camera position with the new FOV.

Hi Folks, I am having a problem with clipping on my scenes. I have looked at my model and it is on the axis and there is no geometry out in space (far away). A few scenes are clipped. If I go from a scene to model extents zoom the clipping disappears. If I go back to the scene it reappears. I can set my field of view from 35 deg to 25 deg, but it seems to be remembered at 35 on my scenes. I reset field of view to 25, go to a scene. Field of view is greyed out. I click Camera, Perspective then Field of View and it is back to 35 deg. I have a bunch of scenes and am trying to layout my final copies but cannot get rid of the scene clipping. Is there any way to globally reset my Field of View so it affects my scenes or do I have to redo everything? Thanks

SketchUp is not a camera. It uses a monitor to display results in a wide variety of sizes and aspect ratios. Rather than try and provide a long list of settings to accommodate the range of possible display devices, it makes more sense to use the vertical reference since almost all computer monitors in normal use have a wider field of view horizontally than vertically. Which angle of view would make more sense if I want to view a sphere from any imaginable angle?

I may well be the one not understanding your question. I’ve uploaded a model with six scenes. Scene 1 is the plan view, scene 2 is the front view, scene 3 is the right view, scene 4 is the rear (back) view, and scene 5 is an isometric view. The clipping is determine solely by zooming in or out to the size you want and then updating the scene. Scene 6 is a perspective view where I have set the FOV to 25 deg and updated the scene (you didn’t specify which version of SketchUp you are using so I uploaded it in 8).

To muddy the waters a little bit; When you import a photo and “photomatch” it (setting the vanishing points), then the angle of view normally changes (about 70-75º normally). However this does not take into account any curvature of the lense; isn’t it a bit pointless trying to be accurate with the angle of view when there is no barrel distortion?

Just a note about the field of view in SketchUp: The FOV numbers do not match the ones given to a 35 mm camera lens. In SketchUp the FOV is measured vertically across the model window, while the shape of the window varies, whereas in a camera the measurement applies to a diagonal of the picture frame that has fixed 2:3 proportions. A SketchUp view with a FOV of 50mm is considerably more wide-angled than in a camera with a 50 mm focal length lens for a view where the width is bigger than the height.

where c {\displaystyle \,c\,} is the speed of light in vacuum, n {\displaystyle \,n\,} is the refractive index of the medium, and Δ f {\displaystyle \,\mathrm {\Delta } f\,} is the bandwidth of the source or λ {\displaystyle \,\lambda \,} is the signal wavelength and Δ λ {\displaystyle \,\Delta \lambda \,} is the width of the range of wavelengths in the signal.

This article focuses on the coherence of classical electromagnetic fields. In quantum mechanics, there is a mathematically analogous concept of the quantum coherence length of a wave function.