This window displays the live image that will be used for recording in the current configuration.
If position information is available, you can change the current slice plane by holding down the shift key and clicking mouse buttons in this window. One click with the left mouse button defines a plane across the current B-scan, perpendicular to the current B-scan. Click and drag with the left mouse button to define a plane along the drag line, perpendicular to the current B-scan. While you are dragging, the images in the `Reslice' and `Manifold' windows may update in real time, depending on the setting of the `CPU & graphics performance' slider in the `Edit setup' panel.
If you define a plane using one of these two methods, you can subsequently change its angle to the B-scan it which it was defined by holding down the shift key and clicking with the middle mouse button in a different B-scan. This defines the third point that the plane is required to pass through.
The intersection with the current slice plane is shown as a green line. If you want to stop display of this line, click on the `Slice' toggle button at the bottom of the window. Remember to toggle the display back on if you wish to redefine the slice plane using the mouse buttons with the shift key.
Without the shift key, the left mouse button can be used to define the cropping of the incoming images. Just hold down the mouse button and drag out a rectangular box. The crop area will be set when you release the button. Of course, you can only make the crop area smaller using this technique. To make it bigger, use the sliders in the `Edit setup' panel. When you crop the preview window, the spatial calibration parameters are automatically updated for the new video crop. If you want to keep the new spatial calibration, make sure that you save the calibration (.sxc) file after you have cropped the image.
The slider at the bottom of the `Preview' window controls its refresh rate. The default is that it displays every frame as it arrives from the ultrasound machine, though you can change this to display, for example, one frame in five. This is useful for computers that have trouble maintaining high graphics refresh rates while acquiring video data. Often, it is the video acquisition that loses out, and Stradx starts dropping frames from the ultrasound machine: if this happens to you, try reducing the `Preview' window's refresh rate.
Calibrated rulers appear along the sides of the `Preview' window whenever the `Measurements' window is open.
The `Wedges' toggle button switches on features associated with one of Stradx's spatial calibration facilities. Further details can be found here.