Planimeter Widget Help

Planimeter is used in conjunction with Edit Data Planes to display an arbitrary plane through the data and enable the interactive outlining of objects in the arbitrary plane. Choosing this from the Stuff menu on the DAVE Master Widget enables a pop-up menu (button 3) when the mouse cursor is in the Display window.

The basic approach is to position the arbitrary data plane so that it intersects the object of interest (see Edit Data Planes for information on how to do this) at one end of the object and more or less perpendicular to its major axis. Once this is done, the object is outlined by picking points around its circumference. Then the data plane is moved along the object (and possibly reoriented slightly) and another outline is created. This process continues until the far end of the object is reached. Outlines do not have to be entered in order, e.g., you can insert an outline on a data slice between two which have already had outlines drawn on them. If you do this, then you must SORT the outlines after they have all been drawn (see SORT on the OPTIONS widget, see below). Outlines cannot, however, be on planes which intersect each other within the region being outlined (they are allowed to intersect outside the object). The options widget controls various display parameters. It also has a menu item (Save Points in Volume Coordinates) for controlling the format the data is stored in (see below). It also sorts the object outlines.

The usage of the planimeter option is patterned after the program "planimeter", which is used for outlining objects a slice at a time.

Initial Menu (button 3 when the mouse is in the Display Window)

Before outlining an object, the outline (i.e. object) must have a label. Choosing the "Label->new" menu item prompts for a name. If some names have already been given, they will appear on the menu and can be chosen directly from the menu. All outlines pertaining to the same object must be given the same name. The "cursor style" menu option does nothing at the moment. The "File to save points" option prompts for a name to which the outlines should be saved. All outlines drawn up to this point, and all subsequent outlines will be written to this file in "pts" format. The "Options" menu item pops up an options widget. See below. "Orient Plane" rotates the image scene so that the arbitrary plane is oriented parallel to the screen. This usually makes it much easier to draw on. Note: sometimes it may rotate by an extra 180 degrees (so you are looking at the plane from what used to be "behind"). Let us know if this occurs.

Second Menu

The initial menu is replaced by the second menu automatically once a label is chosen. The initial menu is returned after the user finishes outlining the object in this slice. This is just the way planimeter does it. Once a label is chosen, the user clicks with the left mouse button at points on the arbitrary data plane (which should be on and in "SURF" mode). (DAVE automatically projects the cursor onto the point on the arbitrary data plane directly behind the cursor position). These points will be connected with line segments. Points can be erased by clicking with the middle mouse button. When the outline is almost completed choose "Close and Write Pts" to close the outline and write out the data to a file. Choose "Write Pts" if you don't want to close the outline. If you want to erase the entire contour choose "Erase". Choose "End Outline" if you want to undo the entire contour, including its label. The "Options" menu item pops up an options widget. This primarily controls drawing options. See below.

Displaying the outlined object as a surface

You must save the outlines created, leave DAVE and then get back into DAVE to view the created objects as full fledged objects (e.g., which can be turned on and off, changed to a surface, have their color and transparency changed, etc.). The file can just be specified on the command line (it is a "pts" file). But to just view the object as a surface, you can change its diplay mode from Options widget, see below.

NOTE: the data in the arbitrary data plane can be rescaled to enhance features. Choose Edit/Map from the DAVE Master Widget. The arbitrary data plane data is in map #1.

Options Widget

Main Window

The name of each outline in the object is displayed here ?? Their order can then be manually changed (if SORT doesn't work) ??

Box on bottom right



This button rearranges the outlines which have been created so that they are in the correct order. It uses a simple technique to decide what this order should be, so if the object twists and turns a lot it may not work entirely correctly. Sorting is necessary if you ever want to display the object as a surface.

Menu Items

Draw Objects as Surfaces

When chosen, this displays objects as surfaces instead of as wireframes.

Draw in Main Window

The default. This lets the user click with the left mouse button directly on the image in the main display window. If this is not chosen the user should choose "Show Plane in Separate Window" and he or she can then draw points in that window instead (see below).

Clear Overlay Plane after Saving

The most recent outline drawn is actually not incorporated directly into your scene until the next outline is begun. It is really in an "Overlay Plane". This causes the outline to always appear "in front" of your data (so it isn't hidden by other data and so the update rates can stay high). If you want the outline to be incorporated directly into your scene as soon as it is done (i.e., the "Close and Write Pts" or "Write Pts" chosen), choose this option.

Hide Planimeter Wireframes

This option erases from the display all of the outlines you have created. They are not deleted, just not displayed. You can redisplay them by unpicking this option.

Show Plane in Separate Window

This takes the arbitrary data plane and "pastes" it flat on the screen in a separate window. You can then draw on it (if "Draw in Main Window" is deselected). Sometimes this is easier than trying to draw on the plane in 3D. It has two main drawbacks. First, you don't see any of the surrounding data which can provide useful context. Second, it takes up a lot of memory and sometimes screen space.

Save Points in Volume Coordinates

By default, when DAVE saves the outlines you have drawn, it uses a coordinate system as if each outline was drawn on a data slice of constant z value (like the planimeter program). Saved with the coordinates is a rotation matrix which tells DAVE (if you read the file back into DAVE) where it really was. Other programs don't know how to read this matrix information. If you choose this option, the actual 3D coordinates of the outlines which you drew will be saved (thus it is not necessary for another program, e.g., "addlines", to know how to interpret the rotation matrix).

Display Outlines from Prev. Slice Too

Display the outlines from the previous slice in yellow. Only correct if the arbitrary data plane is not rotated from its default orientation of displaying XY planes.

Update Surface

This causes the displayed image to be redrawn and internal data structures to be updated ??
Copyright 1995 by Lawrence M. Lifshitz and the University of Massachusetts Medical School. All rights reserved.