Image

Category

Rendering

Function

Renders an object and displays it as an image.

Syntax

This module is accessible only through the user interface.

Inputs

Name	Type	Default	Description
object	object	none	object to be rendered and displayed
renderMode	flag	0	software=0, hardware=1
defaultCamera	camera	no default	the reset camera
resetCamera	camera	no default	reset the camera
bkgndColor	vector or string	"black"	image background color
throttle	scalar	0	minimum time between image frames (in seconds)
recordEnable	flag	0	enable frame recording
recordFile	string	"image"	file name for frame recording
recordFormat	string	"rgb"	file format for frame recording
recordRes	integer	no default	Image resolution for recording
recordAspect	scalar	no default	Image aspect ratio for recording
axesEnabled	flag	0	produce axes
axesLabels	string list	no labels	labels for axes
axesTicks	integer or integer list	15	number of major tick marks (0 to suppress)
axesCorners	vector list or object	input object	bounds of axes
axesFrame	flag	0	flag for axes frame type
axesAdjust	flag	1	whether to adjust the end points to match tick marks
axesCursor	vector	no cursor	cursor position
axesGrid	flag	0	show grid lines on background
axesColors	vector list or string list	appropriate color(s)	color(s) for annotation
axesAnnotate	string list	"all"	annotation objects to be colored
axesLabelScale	scalar	1.0	scale factor for labels
axesFont	string	"standard"	font for labels
intrctnMode	string	"none"	sets interaction mode of window
title	string	"Image"	Image title
axesXTickLocs	scalar list	no default	locations for x-axis ticks
axesYTickLocs	scalar list	no default	locations for y-axis ticks
axesZTickLocs	scalar list	no default	locations for z-axis ticks
axesXTickLabels	string list	no default	labels for x-axis ticks
axesYTickLabels	string list	no default	labels for y-axis ticks
axesZTickLabels	string list	no default	labels for z-axis ticks

Outputs

Name	Type	Description
renderable	object	object, ready for rendering
camera	camera	camera used
where	window	window identifier for the Image window

Functional Details

This module functions much like a combination of AutoCamera and Display. However, it activates the Data Explorer direct-interaction features of the Image window, which are unavailable when you use the combination of AutoCamera and Display. These features include resizing of the image, pan/zoom, 3-D cursors, mouse-driven rotation, navigation in the image, mouse control of the look-to and look-from points, and direct user control of Image-window size. The View Control... dialog box (accessed from the Options pull-down menu in the Image window) permits explicit specification of these features.

Note: Since Image both renders and displays its input, you would not normally pass it an already existing image (because it would be interpreted as a large number of quadrilaterals). If you do have an image (e.g., previously imported or rendered by one of the appropriate modules), you should use the Display tool, without specifying a camera.

While the Image tool is only available while using the User Interface, you can implement your own interactions with an image using SuperviseWindow, SuperviseState, and Display. Thus direct interaction can be implemented from a stand-alone program using DXCallModule (see 13.10 , "Module Access" in IBM Visualization Data Explorer Programmer's Reference), from a program interacting with Data Explorer using DXLink (see Chapter 17. "DXLink Developer's Toolkit" in IBM Visualization Data Explorer Programmer's Reference), or even from a script (see Chapter 10. "Data Explorer Scripting Language" in IBM Visualization Data Explorer User's Guide). See SuperviseWindow for a discussion of these tools.

If it is installed, hardware graphics acceleration is available as one of the Rendering Options... in the Options pull-down menu of the Image window.

Usually you will use only the first parameter, object. The other parameters, which are hidden by default, control aspects of the image which can also be modified by various pulldowns in the menu of the Image window.

To open the Configuration dialog box for Image, you select the Image tool and use the Edit menu Configuration option.

object	specifies the object to be rendered.
renderMode	specifies whether the rendering should be software (renderMode=0) or hardware (renderMode=1).
defaultCamera	is the camera to be used when the Reset button in the View Control dialog box or the resetCamera parameter (see below) is set to 1 (one).
resetCamera	(when set to 1) resets the camera to defaultCamera if that parameter is provided, or the standard "front view" if defaultCamera is not provided.
bkgndColor	specifies the color of the image background as either an RGB color or a color-name string.
throttle	specifies a minimum interval between successive image displays. The default is 0 (no delay).
recordEnable	specifies that the created images are to be saved to a file.
recordFile	is the name of the file to which images are saved.
recordFormat	specifies the format in which the images are to be written. See WriteImage for more information.
recordRes	specifies the horizontal resolution (in pixels) of the recorded image.
recordAspect	specifies the aspect ratio (i.e., the ratio of vertical to horizontal size) of the recorded image.
axesEnabled	specifies that a set of axes is to be drawn around object.
axesLabels...axesFo nt	are (except for "axes" in the name) the same as the corresponding parameters described for AutoAxes.
intrctnMode	specifies one of the following as the interaction mode of the Image window: "camera" "none" "roam" "cursors" "panzoom" "rotate" "navigate" "pick" "zoom"
title	is the title of the Image window.
axesXTickLocs	specifies the list of x-axis tick locations (see AutoAxes)
axesYTickLocs	specifies the list of y-axis tick locations (see AutoAxes)
axesZTickLocs	specifies the list of z-axis tick locations (see AutoAxes)
axesXTickLabels	specifies the list of x-axis tick labels (see AutoAxes)
axesYTickLabels	specifies the list of y-axis tick labels (see AutoAxes)
axesZTickLabels	specifies the list of z-axis tick labels (see AutoAxes)

The first output of the Image tool (renderable) is the object just before rendering (including, for example, any axes attached).

The second output (camera) is the camera used to render object (including, for example, any zooms or rotations applied by direct interactors).

The third output where is the window identifier for the Image window. This can be used, for example, by ReadImageWindow to read back the pixels from the image.

Recording images displayed in the Image window

1. select Save Image... or Print Image... in the File pull-down menu, or
2. use the record... parameters (see above).

Caching of Objects Internally in the Image Tool

The Image tool is implemented as a macro comprising a number of modules. You can control the caching of intermediate results between these modules using the special "Internal Caching" option in the module's configuration dialog box (see IBM Visualization Data Explorer User's Guide, "Using Data Explorer Effectively".

How the Image Window Centers on an Object

The first time the Image tool executes after being placed on the canvas, it "centers" itself on object. From then on, it maintains that viewpoint unless the user explicitly changes it (e.g., by using rotate, zoom, roam, etc.). Thus, if the object is moving in space, you may at times see only part of it or even none of it. You can "reset" the camera at any time with ResetCamera in the View Control... dialog box or by using the Image parameter resetCamera.

Getting the Output Image

If you want to extract the rendered image so that, for example, you can filter it or arrange it with other images (see Filter), then simply pass the first and second outputs of Image to the first and second inputs of Render. Alternatively, pass the where output to the ReadImageWindow module. Using the ReadImageWindow module allows you to capture the pixels from a hardware-rendered image. Note however, that for some platforms, if the image window is obscured (by another window for example) the obscured pixels may not be present in the captured image.

Tracking the Image window with another window

If you want to have two images visible, and want to alternatively control the viewpoint, resolution, etc. of one of the windows while having the second window display a different object from the same viewpoint, simply use the camera output of the Image tool as input to the camera input of a Display tool. The first input of Display should be the other object you wish to view. For an example, see WindVorticity.net.

For more information on using the Image tool in the user interface, see 6.1 , "Using the Image Window" in IBM Visualization Data Explorer User's Guide. Also see Display for information under the following headings:
 "Differences between Hardware and Software Rendering",
 "Rendering Approximations",
 "Using Default Color Maps",
 "Using Direct Color Maps",
 "Changing Rendering Properties",
 "Gamma Correction",
 "Image Caching",
 "Texture Mapping"

See also Color for information on "Coloring Objects for Volume Rendering".

Example Visual Programs

Nearly every example visual program uses the Image tool. ImageTool.net uses the hidden-by-default parameters. Image_wo_UI.net demonstrates a substitute Image macro using SuperviseWindow, SuperviseState, and Display, which can be used independent of the User Interface.

See Also

 Arrange,  AutoCamera,  Display,  Render,  AutoAxes,  SuperviseWindow,  SuperviseState