VideoCAD

Depth of field box

 Parameters

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Depth of field box

 Parameters

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Depth of field box

 Parameters

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Aperture

Auto Iris lens

Boundary resolution

Height

Hyperfocal distance

Insert in report

Focus distance

The button "Specify the focus plane"

Sharpness area bounds

Resolution at distance

Default

Selected cameras

Click to expand
Click to expand

 


Aperture (f-number)

 

The number, characterizing the amount of light, coming through the lens. Set in this combo-box a value, given in the lens specification. If the auto-iris lens is used and the calculation for minimum lighting is required, set the minimum f-number, given in the lens specification. The minimum number characterizes opened diaphragm, at that the depth of field is minimum. If it is necessary to determine the minimum aperture to get the specified depth of the field, then in this box select the number necessary to get the required depth of field.

 

Auto Iris lens

 

If the box is checked, at depth of field calculation the aperture value, computed during 3D modeling illumination, will be used. If the box is not checked, the aperture value, specified in the  box Aperture (F number), is used.

 

Boundary resolution

 

The minimum acceptable resolution in the sharpness area in lines per picture height (LPH). At that we should remember that we won't get better resolution than other video system components can give. The boundary resolution should not exceed the real resolution with the in-focus image. The resolution on the calculated bound of the sharpness area will be equal to the specified boundary resolution, and inside the sharpness area the resolution will be higher. Changing the value in this box we can get the sharpness areas for different resolutions.

 

Height

 

Height of measuring Depth of Field in the horizontal projection.

If the main optical axis of the camera is not parallel to the horizon, the Depth of Field in the horizontal projection depends on the height above the ground.

 

In multi-level 3D projects the height of the ground surface equals to the base height of the active camera.

 

The AUTO indicates that the height is equal to the middle height between the view area lower bound height and the view area upper bound height.

 

Hyperfocal distance

 

It is calculated basing on the lens focal length of the active camera, aperture and boundary resolution. If the lens is focused on the hyperfocal distance, then the sharpness area stretches from the half of this distance to the infinity. In this case the sharpness area will have the maximum extension.

 

Insert in report

 

If the box is checked, the calculation results of the active camera depth of field will be included in the text file, getting when Text report.

 

Focus distance

 

Minimum distance from the lens to the plane, perpendicular to the main optical axes, on which the lens is focused. Sharpness area bounds depend on the focus distance.

 

The button "Specify the focus plane

 

With the Depth of Field box opened, in the horizontal projection, but in the graphical editing state of the active camera in the vertical projection too can be seen:

 

sharpness area (heavy blue line);
plane at the hyperfocal distance (heavy turquoise line);
plane at the focus distance (thin turquoise line).

Line types can be changed in the Options box.

 

Click to expand
Click to expand

 

After clicking this button:

A click on the view area set up a new focal plane location. At that all other parameters are recalculated.
When moving the cursor over the view area of the active camera on the Status bar at the bottom of the graphics window the current distance from the lens and the resolution in the cursor point are displayed.

 

In the horizontal projection calculations are performed at the height of measuring Depth of Field.

 

Sharpness area bounds

 

Near and far sharpness area bounds. The far bound can amount to infinity.

 

Resolution at distance

 

If in the Distance box to specify the distance from the lens, then in the Resolution box the resolution at this distance can be seen.

At that it is necessary to remember that we won't get better resolution than other video system components can give.  

 

Default

 

Clicking this button assigns default depth of field parameters to the active camera:

Boundary resolution = 0.7* Phor/Aspect ratio;

where:

0.7 - Kell factor;
Phor - horizontal number of pixels (minimum value from number of pixel of the image sensor and the number of pixel specified on the Processing tab);
Aspect ratio - a ratio of Horizontal frame size to vertical one;
Height=AUTO;

 

Selected cameras

 

If this box is checked, clicking on the Default button assigns default depth of field parameters to all selected cameras at once.

 

 

See also: General information on the depth of field in CCTV, Example of Depth-of-field calculation, 3D Video main menu>Depth-of-field, Checking Depth of Field in horizontal projection.