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Pixel density

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Pixel density

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Pixel density

 Tools

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Pattern

Active camera

Edit/Save

Vert./Hor.

Pattern criterion

Height

Object height (width)

Draw Legend

Blend/Hatch

Assign

To selected cameras

Vert.(Horiz.) number of pixel

Active camera

Table of regions

Resolution

Field of view

Distances to the far borders of regions

Field of View sizes at far borders of regions

Type of hatching combo box

Colors of regions button

Expanded image from the Table of regions

Digital ZOOM

From file, To file, Default

 

Click to expand
Click to expand

 


 

Pattern

 

In this combo box the name of the chosen pattern of pixel density is shown.

You can choose any pattern from 30 patterns of pixel density. Parameters of the chosen pattern are displayed and can be edited in the Pixel density box.

The name of the pattern can be edited in this box, when the Edit button is pressed.

 

As a result of right-click on the combo box a pop up menu will appear. Selecting the Default patterns item, you can erase all changes in the patterns and return to the patterns set by default in current version of VideoCAD.

 

The box is inaccessible when the Active camera box is checked.

 

Active camera

 

If the checkbox is checked, a pattern assigned to the active camera is automatically displayed in the pixel density box. The Pattern combo box will become inaccessible for editing.

 

Edit/Save

 

Edit the chosen pattern. Clicking on the Edit button makes parameters of the chosen pattern accessible for editing. The button caption is changed to Save - stop editing and save the modified pattern.

 

Vert./Hor. switch

 

The switch allows to choose direction (horizontal or vertical) to which the pattern criterion must be applied.

If Vert. is checked then the Pixel per meter is the number of pixel per meter along the vertical, the Field-of-view height is the height of the Field-of-View, the Pixel for object is the number of pixel covered by the object along the vertical, the % of Field-of-view for object is a part (%) of the Field-of-View covered by the object along the vertical;
If Hor. is checked then  the Pixel per meter is the number of pixel per meter along the horizontal, the Field-of-view width is the width of the Field-of-View, the Pixel for object is the number of pixel covered by the object along the horizontal, the % of Field-of-view for object is a part (%) of the Field-of-View covered by the object along the horizontal.  

 

The switch is accessible for editing in the Editing mode.

 

When calculating the pixel density, rotation of the camera around its axis by default does not affect the position of the vertical and horizontal in the frame.  Horizontal and vertical positions are tied to the camera and not to the scene. You can change this rule, using the Pixel density and rotation checkbox in the Options box .

Changing the pixel density under the influence of the lens distortion is considered along radial rays from the center of the frame to the edges, without distinguishing between horizontal and vertical.

 

Pattern criterion

 

In the box you can choose a criterion according to which regions in the pattern will differ.

 

You can choose one from 4 criteria:

Pixel per meter (Pixel per foot) - vertical (horizontal) pixel density (pixels/meters, pixels/foot);.
Field-of-view height (width) - vertical (horizontal) field of view size (meter, foot);
Pixel for object - vertical (horizontal) number of pixels covered by an object of the height (width) specified in the Object height(width) box (meter, foot); .
% of Field-of-view for object - the part of the frame height (width) covered by an object of the height (width) specified in the Object height(width box (meter, foot).

Direction of the criterion (vertical/height or horizontal/width) can be specified by the Vert.//Hor.switch

 

Meters or feet as a unit of height are selected automatically depending on the format of measurements in the project.

 

 

For the criteria Pixel per meter (Pixel per foot), Pixel for object  the pixel density depends on the number of pixels along vertical or horizontal.

In calculation the minimal number of pixels from parameters of camera image sensor and parameters of output image is used.

Number of pixels of image sensor is specified on the Sensitivity and Resolution box.

Number of pixels of output image is specified on the Processing tab of the Image parameter panel.

If number of pixels is not set (N/A), calculation is performed for vertical 720 pixels (or horizontal 1280 pixels).

 

Rotation of the camera around its axis by default does not affect the position of the vertical and horizontal in the frame.  Horizontal and vertical positions are tied to the camera and not to the scene. You can change this rule, using the Pixel density and rotation checkbox in the Options box .

 

Pattern criterion of pixel density for panoramic cameras must be based on the pixel density (Pixel per meter (Pixel per foot), Pixel for object), but not on the field of view size. Criterion Field-of-view height, % of Field-of-view for object are not suitable to panoramic cameras, because of panoramic cameras have not a stable field of view.

 

The box is accessible for editing in the Editing mode.

 

Height

 

Height of measuring the pixel density in the horizontal projection (height of the horizontal red line on the picture).

 

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

 

If in the Height box AUTO is chosen and in the View area projection bounds and Shadow buttons the Within projection is chosen, then calculation of pixel density in the horizontal projection is carried out at the middle height between the view area lower bound height and the view area upper bound height.

 

If in the Height box of the Pixel density box, AUTO is chosen and in the View area projection bounds and Shadow buttons the 2 levels is chosen, then calculation of pixel density in the horizontal projection is carried out at the view area lower bound height

 

The box is accessible for editing in the Editing mode.

 

Object height (width)

 

Height (width) of the object for the criteria associated with an object: Pixel for object and % of Field-of-view for object.

 

The caption is changed according to the Vert./Hor. switch.

 

The box is accessible for editing in the Editing mode.

 

Draw Legend

 

Draw legend of the current Pixel density pattern on the Graphics area. After choosing this button specify place of the legend on the Graphics area of the Graphics window.

You can select font type on the font type panel before placing or after double clicking near to the left top corner of the legend.

By means of font type you can change size and color of the legend. You can also make the legend scalable or nonscalable.

Legend is tied with his Pixel density pattern. If parameters of the pattern is changed then the legend will be changed too. You can place several legends of different patterns on the same layout.

 

Blend/Hatch

 

Show the regions in the Pixel density box hatched or filled by blend translucent colors.

 

This box affects displaying regions in the Pixel density box only. Hatch or fill regions in the Graphics window can be determined separately for each camera using the Fill projections button.

 

Assign

 

 

Assign chosen pattern to the Active camera. If the To selected cameras box is checked, then the chosen pattern is assigned to all selected cameras.

 

Vert.(Horiz.) number of pixels

 

 

Attention! The purpose of this combo box differs in Starter, Lite and Professional versions!

 

The caption is changed according to the Vert./Hor. switch.

 

Vertical (horizontal) number of pixels for modeling images on the far bounds of regions. Images on the bounds of regions depend not only on the criterion value, but also on the number of pixels.

 

Thus, for criteria related to the number of pixels which covers a specified height (width) (Pixel per meter, Pixel for object) value of the criterion determines the pixel density, ie how detailed the scene is photographed. In this case, Vert.(Horiz.) number of pixels determines the size of the field of view.

 

Conversely, for criteria related to the height (width) of the field of view (Field-of-view height(width),% of Field-of-view for object) criterion value determines the size of the field of view. In this case, Vert.(Horiz.) number of pixels determines the pixel density, ie how detailed the scene is photographed.

 

In the Professional version this box affects only the images in the Resolution and the Field of view columns in the Pixel density box. This box does not affect the regions in the Graphics window.

For calculation of regions in the Graphics window the minimal number of pixels from parameters of camera image sensor and parameters of output image is used.

Number of pixels of image sensor is specified on the Sensitivity and Resolution box.

Number of pixels of output image is specified on the Processing tab of the Image parameter panel.

If number of pixels is not set (N/A), calculation is performed for vertical 576 pixels (or horizontal 768 pixels), what corresponds to analog camera.

 

Rotation of the camera around its axis by default does not affect the position of the vertical and horizontal in the frame.  Horizontal and vertical positions are tied to the camera and not to the scene. You can change this rule, using the Pixel density and rotation checkbox in the Options box .

 

The box is accessible for editing if the Active camera box is not checked.

 

 

Active camera

 

 

When this box is checked, the number of pixels of the Active camera is assigned to the Vert.(Horiz.) number of pixel box. The Vert.(Horiz.) number of pixel box becomes inaccessible for editing.

 

For calculation the minimal number of pixels from parameters of camera image sensor and parameters of output image is used.

Number of pixels of image sensor is specified on the Sensitivity and Resolution box.

Number of pixels of output image is specified on the Processing tab of the Image parameter panel.

If number of pixels is not set (N/A), calculation is performed for vertical 720 pixels (or horizontal 1280 pixels).

 

Rotation of the camera around its axis by default does not affect the position of the vertical and horizontal in the frame.  Horizontal and vertical positions are tied to the camera and not to the scene. You can change this rule, using the Pixel density and rotation checkbox in the Options box ..

 

Table of regions

 

In rows of this table you can see and edit parameters of regions of the chosen pixel density pattern.

 

The bottom row of the table corresponds the nearest to the camera region.

 

On the first column of the table, on the background rectangles filled by a color assigned to the region, the Name of the region and the Criterion value at the far bound of region are displayed.

 

 

       Resolution column

 

The Resolution column contains fragments of images with people at the far bounds of each region. These are fragments of images, not whole images. Field of view of the fragments is less than the real field of view, but the resolution of people corresponds the real images exactly.

 

On the images in the Resolution column, you can see with which resolution people at the far bound of each region will be visible.

 

       Field of view column

 

The Field of view column contains whole reduced images of people with the field of view at the far bounds of each region. Resolution of these images is less than resolution of the real image, but the field of view corresponds the real images exactly.

 

On the images in the Field of view column, you can see which part of the field of view people at the far bound of each region will cover.

 

Images in Resolution and Field of view columns are automatically generated according to the criterion value of each region and the Vert.(Horiz.) number of pixel value.

The images visualize the boundary values of the criterion.

 

The height of "men in blue shirt" is 2 meters (about 6.5 feet).

 

       Distances to the far borders of regions

 

The table displays the distances to the far boundaries of regions for a camera with the number of pixels displayed in the Vert.(Horiz.)Number of pixels box. If the checkbox Active camera is checked then the distances to the far bounds of regions for the active camera are displayed.

 

 

For fisheye cameras and criteria related to field of view size, distance calculation is not possible.

 

       Field of View sizes at far borders of regions

 

On the edges of the images in the field of view column the sizes of the field of view at the far bounds of regions for a camera with the number of pixels displayed in the Vert.(Horiz.)Number of pixels box are displayed. If the checkbox Active camera is checked then the sizes of the field of view at the far bounds of regions for the active camera are displayed. If the checkbox Active camera is not checked, then only one size is displayed depending on the direction (horizontal, vertical) for which the number of pixels is displayed in the Vert.(Horiz.)Number of pixels box.

 

 

For fisheye cameras, it is not possible to calculate size of the field of view.

 

 

Moving the mouse over the image shows an expanded copy of this image at the top of the box.

 

Left click on the image opens the Table of images. As a result of clicking on the image in the Resolution column, a table of resolutions will appear, and as a result of clicking on the Field of view column, a table of sizes of the field of view will appear.

 

Right-clicking on any image in the Table of Regions brings up the pop-up menu. Using this menu, you can quickly change the image in the Table of Regions.

 

 

In the Editing mode the Names of regions and the Criterion values become accessible for editing. In addition the Type of hatching combo boxes and Colors of regions buttons appear.

 

 

In the Type of hatching combo boxes you can choose type of hatching for each region.

 

Hatching will be visible in the Pixel density box when the Blend/Hatch box is not checked. In the Graphics window, hatching of the chosen  type will be shown for cameras, which have chosen Hatching in the menu of the Fill projections button.

 

Color of region is the same for filling and for hatching.

 

 

 

Expanded image from the Table of regions

 

The images in the Table of regions are small. But if you move the mouse cursor to any of the images, then its expanded copy will appear at the top of the box.

 

To close the expanded image and access the tools under the image - just click on it.

 

Clicks on the buttons open the Table of Images.

The left button fills the table only by images from the Resolution column. The same result can be obtained by clicking on any image in the Resolution column.

The right button fills the table only by images from the Field of View column. The same result can be obtained by clicking on any image in the Field of View column.

The middle double button fills the table by images from both columns.

 

The expanded image has a pop-up menu that coincides with the pop-up menu of the Table of pictures.

Digital ZOOM

 

 

By moving the slider, you can enlarge the pictures in the Resolution column. On the left half of the slider the scaled pictures will be displayed with constant resolution and variable field of view. In the right half of the slider scale, pictures will be displayed with a constant field of view and variable resolution.

 

From file, To file, Default

 

 

Using To file or From file buttons you can save pixel density patterns to file or load from file. As a result of clicking on the Default button, patterns installed by default in this version of VideoCAD will be restored.

 

 

See further : Work with the Pixel density box.