Module: Image Ortho Projections ()

Description:

This module computes a shadow projection of a 3D uniform scalar field (an image volume) onto the three major planes (xy, xz, yz). Color fields and multi-channel fields are also supported. Maximum intensity projection or averaging can be chosen as projection method. This module is especially useful for data containing line-like structures like neurons or angiographic data.

If attached to a 1-component scalar field, the location of voxels containing maximal values can be investigated interactively using the module Projection Cursor.

Press the Apply button to recompute the projection.

Connections:

Data [required]
The data set to be projected. Uniform scalar fields, uniform color fields, and uniform multi-channel fields are supported.

ROI [optional]
Connection to a module providing a region-of-interest ROI Box. If such a module is connected, only the volume inside the ROI is projected. Alternatively, this port can be connected to Cylinder Slice, which defines a cylindrical ROI.

Ports:

Channels

This port is displayed if the module is connected to a multi-channel field. It allows you to turn individual channels on or off.

Show

The three first toggles can be used to turn off the yz-, xz-, or xy-slice. The last toggle dragger enables showing/hiding the dragger visibility which could be used to restrict the visualization of this display module. This toggle is enabled only if the restrict option is checked.

Options

interpolate: Bilinearly interpolate between pixels on the projection planes. This in general gives better image quality and less aliasing. However, sometimes the resulting image may appear somewhat blurred.
inverse: Invert colormap display values. Inversion is done after mapping data values to intensity values via the selected colormap.
restrict: Enable restricting the visualization to a the region-of-interest. Minimum/Maximum x-, y-, and z-coordinates of the region-of-interest could be controlled with a dragger (see dragger check box) or with the ports Min. slice and Max. slice.
lighting: Specifies whether the slices should be illuminated or not. If lighting is on the luminance of the slices changes when the scene is rotated.

Min. slice

This port is only visible if restrict option is checked. It controls the Minimum x-, y-, and z-coordinates of the region-of-interest.

Max. slice

This port is only visible if restrict option is checked. It controls the Maximum x-, y-, and z-coordinates of the region-of-interest.

Mapping

Mapping

The first menu specifies the projection mode. Maximum searches the largest data value in each projection ray, Minimum for the smallest one. Average computes the average data value for each projection ray. The options depth and depth + max are only available for scalar fields. If depth is chosen on each slice the depth of the pixel containing the maximum value is depicted, instead of the maximum value itself. If depth + max is chosen, first an ordinary maximum intensity projection is computed and mapped to a gray image. Then the gray image is multiplied with a pseudo-color image of the depth values. This allows you to visualize both projected structures and depth information at once.

The second menu specifies how the projected data should be mapped to color or intensity. Two modes are available, Histogram, and Colormap. These modes are identical to the ones described for the Ortho Slice module. Colormap mode is available for color fields and for multi-channel fields but computes automatically the data color information.

Colormap

The colormap which is used when the mapping type is set to Colormap.

Contrast Limit

This port is only visible if Histogram equalization is selected. The number determines the contrast of the resulting image. The higher the value, the more contrast is contained in the resulting image.

Commands:

createImage <image base name>
This command creates 2D images from the projections in the Project View. Between one and three images are created depending on the port Show. The image base name can be omitted.

setTransparency <alpha>
Set transparency of projections. A value 0 makes it completely opaque, 1 completely transparent.