MEASURE Measuring Distances from the Screen

MEASURE Measuring distances from the screen

The figure (right) shows the MEASURE control panel (which can be accessed by pressing M as well as from the "Tools" menu). From D3PLOT 10.0 onwards D3PLOT can keep track of up to 100 measurements. Each measurement can be in a different window or it can be between different models within the same window. Select the first measurement Select the previous measurement Goto measurement (n) Select the next measurement Select the highest measurement defined + 1. Once a measurement has been defined it will be drawn on the screen along with the corresponding value. By default all measurements will be drawn along with the values.

	If this option is selected then the current measurement will be incremented as soon as enough points/nodes/parts have been selected. The preference measure_auto_create can be set to toggle the initial status of Auto Create.
	Show All measurements, the Current measurement, or None.
	Draw the measurement lines in Wireframe mode (so they are always visible), or Hidden mode (so they are within the 3D model).
	Specifies the colour used to draw the current measurement.
	Specifies the colour used to draw all measurements apart from the current measurement.
	Specifies a name to display next to the measurement.
	Display magnitude and vector values next to each measurement.
	This option will add labels to any nodes or parts used to define the measurement.
	This option will remove the square of background colour from behind the name, magnitude, and vector annotation on the plot.

Specifies the format of the magnitude and vector values displayed on the plot.

The seven measurement functions here are described in below.

All of them use screen-picking with the cursor to select points, nodes or parts and report results in a special table in this panel.

"Point" functions:	Screen points are arbitrary locations on the screen picked with the cursor. They are not located on or attached to the model in any way. Distances reported for screen points are reported in screen space units.
	Point to Point Measuring the distance between 2 points Pick pairs of points with the cursor, and the distance in screen space units between them is reported. (Screen space units have the scale of model space, but projected onto the 2D plane of the screen.)
	Point angle Measuring the angle between 3 points Pick three points with the cursor. The angle (on the 2D screen plane) between vectors P1P2 and P1P3 is reported.
Node functions:	Nodes are picked on the model, and all distances and coordinates are reported in model space units. The nodal coordinates used are those of the state currently in core.
	Node to Node Measuring the distance between 2 nodes Pick two nodes with the cursor. The distance in model space units between them on XY, YZ and ZX planes and in 3D space is reported.
	Node angle Measuring the angle between 3 nodes Pick three nodes with the cursor. The angles on XY, YZ, ZX planes and in 3D space between vectors N1N2 and N1N3 are reported.
	Node to Origin Nodal position and distance from [0,0,0] Pick a node with the cursor. Its current coordinates and distance from the origin in model space units are reported.
Part functions:	Parts are picked on the model (limited to SOLID, TSHELL and SHELL parts), and all distances and coordinates are reported in model space units. The coordinates used are those of the state currently in core.
	Node to Part Shortest distance between a node and a part Pick a node and a part with the cursor. The shortest distance in model space units between them on XY, YZ and ZX planes and in 3D space is reported.
	Part to Part Shortest distance between two parts Pick two parts with the cursor. The shortest distance in model space units between them on XY, YZ and ZX planes and in 3D space is reported.

Offsets

From D3PLOT 20.0 onwards measurements consider any offsets by Deform (for example Shift deform) or in model space for the coordinates in measure calculations. When these Deform and Model space options are turned off, measures are calculated from the actual coordinates of the nodes.

Local Coord Sys

Measurements can be made within a local coordinate system if desired. Press the RETRIEVE button to select a coordinate system from either the 'csys.loc' file (defined in the Shift Deformed panel) or any *DEFINE_COORDINATE definitions in the ZTF file.

Deformed coords / Undeformed coords

If a coordinate system defined by nodes is selected (i.e. from the 'csys.loc' file or a *DEFINE_COORDINATE_NODES definition in the ZTF file), you will have the option to use either the deformed or undeformed coordinates of the the nodes. If you select deformed the coordinate system will update with the model.

Reference State

Measurements can be relative to the value at a chosen reference state. Select the reference state by entering a value in the "State:" or "Time:" text boxes, or by moving the slider. If the "Time:" box is used, the closest state to that time will be selected.

Relative magnitudes of distances and angles are calculated by subtracting the reference state values from the current values using simple scalar subtraction. Below are the equations used in the calculations:

• Relative Displacement Magnitude = (Magnitude at current state) - (Magnitude at reference state)
• Relative XY Angle = (XY angle at the current state) - (XY angle at the reference state)
• Relative YZ Angle = (YZ angle at the current state) - (YZ angle at the reference state)
• Relative ZX Angle = (ZX angle at the current state) - (ZX angle at the reference state)

The X, Y, and Z displacement vectors displayed are unaffected when the reference state is active.

Typically, relative magnitude measurements would be useful in the case where the measurement is done for uniaxial load cases. An example is shown in the first model shown below where a crush tube is under compression. By setting the reference state to state 1, the user can immediately tell that a compression of about 278.2 units has occurred.

There are situations where measuring relative to another state isn't very meaningful. This is illustrated in the second model. For example, if you measure the distance between two nodes and one rotates 90 degrees around the other, the relative distance remains zero. In the images below, the first image shows the beam in a horizontal position (state 1, the reference state), and the second image shows the beam rotated to a vertical position (state 2).

The vector distance along vector N1 to N2 in both current and reference states are 10 units, so using current magnitude minus reference magnitude we get 0.0. However, because the vectors in the two states are at a large angle to each other this result is not very useful. Relative results are only meaningful when displacements in the two states are down a very similar vector.

Modifying a measurement

After you have created a measurement you can modify the selected NODEs (or PARTs) by right-clicking on the textbox and selecting PICK

Export to XY_PLOT

Make a graph of distance for the current measurement. Four separate curves will be generated for each measurement containing the X, Y, Z and magnitude components using all time-states in the model. The plots can be saved as curve files or transferred to T/HIS if the T/HIS link is open.

Export ALL to XY_PLOT

Make a graph of distance for all measurement. Four separate curves will be generated for each measurement containing the X, Y, Z and magnitude components using all time-states in the model. The plots can be saved as curve files or transferred to T/HIS if the T/HIS link is open.

Resuming a Measurement after using Quick Pick

If you press the shortcut key 'q' to swap from measurement picking to quick pick, e.g. to blank some parts the menu will change to display the RESUME MEASUREMENT button. Click this when you have finished using quick pick.