D3PLOT 22.1

LEVELS... Setting Number of Contour Levels, their Ranges, Colours and Number Format

LEVELS... Setting number of contour levels, their ranges, colours and number format

By default contouring is set to have:

13 levels
Automatically computed values, scanned over all frames
Colours from blue (low) to magenta (high)
Automatic number format

These default settings are shown right, the LEVELS sub-menu.

Contour Level settings are stored separately for each component category. If for example the number of levels is changed to 13 and the contour levels are set to " User def "ined values for the "Stress" component category then these options will be used whenever a "Stress" component is plotted.

As well as being stored for the "Stress" category the new settings will also become the default for any categories that the user has not explicitly stored settings for.

If after setting the number of levels for "Stress" the user sets the number of levels for "Strain" to 10 then 10 will be used for "Strain" and for any categories that the user has not explicitly stored settings for. If the user then swaps back to "Stress" component the previously set number of levels (13) will be used.

NOTE : If the data component is set to FORMABILITY then a special set of options will be displayed instead of this menu, see Special options for FORMABILITY.

Setting contour levels (Automatic, Max_&_Min, User_Defined and Linear/Logarithmic)

By default contour levels are AUTOMATIC over all frames. This means that the maximum and minimum values are computed prior to each plot, and the resulting bands spaced evenly between these.

Automatic contour bands can be computed in two ways:

Automatic mode	During a static plot	During an animation
Over all frames	Contour bands are automatically scaled to the max and min values in this plot only. (The same behavior in all three modes.)	The "envelope" of max and min values of all frames making up the animation are calculated, then every frame of the animation is contoured using this same single range of values. So the contour bands and values are the same in every animation frame.
Each frame separately		The max and min values in each frame are computed separately, and each frame is auto-scaled to its own set of values. So the contour bands may change in each frame, and the effect is the same as a series of individually auto-scaled static plots.
Over all windows		The "envelope" of max and min values of all frames across all the windows in the current page making up the animation are calculated, then every frame of the animation is contoured using this same single range of values. So, the contour bands and values are the same in every animation frame across all the selected windows in the current page.

In the figures above the contour levels have been set manually: the max and min values only are set in the left figure, user-defined levels for each band are set in the right figure.

MAX_&_MIN levels have been selected, and the upper and lower values defined. The intermediate values are interpolated linearly and filled in for you. They can then be changed manually by enabling the tick boxes. This will switch to user-defined contours explained next.

The figure (right) shows the same panel set up for the plot in (b) above. USER_DEF ined levels have been chosen, and apart from the minimum and maximum one user-defined level has been specified. The levels explicitly specified can have uneven intervals. When the tick boxes for levels are off, the threshold value is calculated with uniform intervals.

Also, it is possible to turn off the first and/or last level, which will then be calculated automatically like in Auto all frames.

New levels for user-defined contours can be inserted or existing levels deleted with the popups at the text boxes with the band threshold values.

User-defined contours are only meaningful when the levels explicitly specified are in monotonic order. When this is not the case, the ticked levels can be sorted into ascending order with the Sort levels button.

Hint:

Choose MAX_&_MIN first, fill in upper and lower-bound values, then turn on tick boxes for explicit levels in between. The interpolated intermediate values are preserved when turning on a level and may give some indication what you might want to specify.

All levels between the minimum and the maximum will be interpolated linearly by default such that all bands have got the same width. This also applies to User defined levels where checkboxes are off. As alternative to that Linear interpolation there is Logarithmic interpolation, where the factor to get from one threshold to the next will always be the same. Between any two positive numbers this is the same thing as replacing them with their logarithm, interpolating linearly and reverse the logarithm.

For example, logarithmic interpolation with 6 levels from 1 to 1000000 will give the log values 0 to 6, and interpolated values would be 10^0, 10^1, 10^2,... 10^6.

Logarithmic interpolation is also available between two negative numbers, for example 6 levels from -1000000 to -1 would give thresholds -10^6, -10^5, ..., -10^1, -10^0.

When logarithmic interpolation between zero and a non-zero number or between two numbers of opposite signs are requested, D3PLOT will automatically insert numbers close to zero and interpolate the negative and positive ranges logarithmically separately. By default it will divide the extremal thresholds by 2 recursively, but other factors can be obtained by switching to user defined contour levels where thresholds close to zero are specified explicitly with checkboxes turned on.

convert to log scale

The DISPLAY ALL EXPONENTS switch will put an exponent on each contour bar value rather than one exponent at the bottom of the bar that applies to all values. This is useful if the scale has been converted to a log scale so that the individual values can be shown with enough precision.

display all exponent

Computing contour bands over multiple windows and models

Where there is more than one window, possibly showing a different component, on a model; or more than one model in the database then contour levels are computed as follows:

AUTOMATIC contours:

For each active window ( Wn tab selected):

The max and min values of all visible elements in all models is computed
These become the max/min bounds for that window
Changing what is displayed in that window will update these bounds

Each window is independently calculated, regardless of the contents of other windows for auto all frames and auto each frame contour modes.

During animation exactly the same rules apply, except that the "envelope" of values from all frames is used to calculate the max & min values.

MAX & MIN contours:

For each active window ( Wn tab selected):

The user-defined max and min values are applied to that window, regardless of contents.

Applying the same contour bands to all windows It is often the case that you have several windows, and you want to have the same contour bands in all of them. To do this:
If you want to specify the bands to be used:	Make sure that the Wn tabs for all required windows are selected. Choose MAX_&_MIN levels Set the required levels.
If you want to find the envelope of all windows, derive a max & min value from that, then set it in all windows.	Make sure that the Wn tabs for all required windows are selected. Choose AUTOMATIC levels. Perform plots in all windows to update their local bands. If you want values over an animation then animate all these windows to force computation of the "envelope" max/min values in each. Then select MAX_&_MIN
The second method works because when you switch from AUTOMATIC to MAX_&_MIN D3PLOT computes the "envelope" of max/min values from all active windows, and applies this as the default values for MAX_&_MIN mode.

It is important to understand the distinction between automatic contouring over animation frames , and automatic contouring at a given state .

Automatic contour bands during Animation

Case 1: When Automatic all frames mode is in use.

During an animation , or when a particular frame of an animation is displayed statically:

For each window D3PLOT will scan all selected states and find the max and min contour values.
If the window contains more than one model the max and min over all models in the window is found.

These max and min values become the contour bounds used for the animation, or when any frame of the animation is displayed, with the intention that contour bands in any frame will have the same values.

Case 2: When Automatic each frame mode is in use.

Each frame of the animation is auto-scaled separately and whenever a frame is display, either statically or when animating, the contour bands will be "local" to that frame.

In this mode the contour bands will usually change during each frame of an animation, therefore the values assigned to a particular contour band will not normally be the same in successive frames.

Case 3: When Automatic all windows mode is in use.

During an animation , or when a particular frame of an animation is displayed statically:

For each window D3PLOT will scan all selected states and find the max and min contour values.
If the window contains more than one model the max and min over all models in the window is found.

These max and min values across all frames and windows in the current page become the contour bounds used for the animation, or when any frame of the animation is displayed, with the intention that contour bands in any frame will have the same values.

Commands which display animation frames are:

[ > ] Play to initiate an animation, either at the top of a graphics window or in the "States" panel.
Any of the << |< >| >> frame positioning commands either at the top of a graphics window or in the "States" panel.
Using the state slider at the top of a graphics window.
Using the <shift> + <arrow key> short cut to toggle through frames.

Automatic contour bands during static state display

During static display of a specific state :

For each window D3PLOT will find the max and min of all models in that window at that state only.

If you subsequently move on to another state then the contour bounds will change as the new max and min values for that state are used instead.

Commands which display static states are:

Any explicit data plotting command (eg SI , CT , ..) while not animating.
Using the state slider in the "States" panel.
Setting an explicit state number or time in the "States" panel.
Using the <arrow keys> (no shift) to toggle through states.

A useful trick if you want to "animate" a series of states, but to auto scale contours to each state individually, is to use the <arrow keys>: hold them down letting them auto-repeat and D3PLOT will cycle through states with specific contour bands for each state.

Why is there a distinction between "frames" and "states"?

It is true that for most transient analyses "frames" will be equivalent to "states", however there are some cases where this is not the case:

When plots are interpolated by time the frame vs state equivalence no longer holds, and typically there are many more frames.
The user can choose to animate only a subset of the available states, reducing the number of frames.
In frequency domain (modeshape) analyses each "state" is a mode, and animation frames cycle through +/- 180 degrees at that mode.
Similarly "static" analyses with a series of loadcases use frames to animate each case in a quasi-modal fashion.

Preserving this distinction makes D3PLOT more flexible and provides more options for contouring animations.

For more details about animation, frames and states, and how to specify them, see Animation How to Display, Control, Store and Retrieve Animation Sequences on Animation.

Visible faces vs All faces

By default D3PLOT only uses the values on the visible faces of 3D elements when using AUTO or AUTO EACH to calculate the contour bar limits for SI, CT or LC plots.

If an internal face has a higher or lower value then it is reported in the top left of the window but the value is not used for the contour bar range.

(If internal faces are turned on then the contour bar includes the values)

If this option is changed to Use All Faces D3PLOT use the internal face values when calculating the contour bar range.

This option can be set as the default in D3PLOT via the preference option.

d3plot*contour_bar_3d_faces:

Clicking on the contour bar to set levels

As an alternative to the explicit methods of setting contour bands described above it is also possible to set and restrict values by clicking on the contour band display itself.

On a data-bearing plot hover the cursor over the contour level bands, and the cursor symbol will change to CONT/OPTS , and the following options are then available:

Left mouse: limits the display to only those items within the selected band
Middle mouse: reverts to automatic contour levels
Right mouse: maps the options menu shown here

Items in band (left mouse)	Restricts the display to those items in the selected band, but does not alter the overall contour band limits. The effect is based on the centre value of elements, so if contouring is on (the default) you may see gradations of value outside the limits of the band chosen. To prevent this turn averaging off, or select a plotting mode (such as CL oud plots) which shows centre values only.
Scale to band	Resets contouring to max/min using the upper and lower values of the band chosen. Display is not limited to this range, so items outside the range will still be drawn.
Limit to band	As Scale to band , but also sets limiting values to the original band's max/min, so only elements within the original band are shown.
Reset to auto all states (middle mouse)	Resets contouring to Automatic (all states), and turns off limiting values if switched on by one of the options above.
Reset to auto each state	Resets contouring to Automatic (each states), and turns off limiting values if switched on by one of the options above.
Map contour panel	Is the equivalent of selecting Contour > Levels .

Restriction to a band is carried out using the Contours > Limiting Values function described in LIMITING_VALUES... Limiting What is Contoured by Value Range . In effect the functions here set the upper and lower bounds, and turn on limiting. You can adjust these further by hand if you wish.

Changing contour band colours

By default colours range from blue (low value) to magenta (high value), and the colour range is set up automatically. Internally there are 15 standard colours to choose from, and any contour band may be assigned any colour.

To change a colour click on its number then select an alternative standard colour from the panel, or define your own arbitrary colour.

SAVE CONTOUR COLOURS	Will save the contour colours to the oa_pref file so they will be reloaded when a new session of D3PLOT is started. This can be useful if you regularly modify the colours, e.g. setting the minimum value to grey.
RESET	Will reset contour colours to their default range for this number of levels.
REVERSE	Will reverse the current colour range for this number of levels.

The default colours are not colour-blind friendly and when printed in greyscale, for example in a report, it is not possible to distinguish the different contour bands.

To address this there are some new contour ramps which can be selected from the popup above the contour ramp colours. These are colour-blind friendly and when printed in greyscale each contour band is distinguishable from the others.

Note 1:	Contour bands define the upper and lower values of each discrete band. For solid contoured plots (i.e. CT, SI) each band lies between these limits. For line contoured (LC) plots each line will lie at the mid-point of its band.
Note 2:	Colour tables for contours are stored separately for each number of contour levels. So if you change colours for (say) 6 contour levels this will not affect colours for any other number of levels.
Note 3:	During SI shaded-image plots the current number of contour levels is mapped onto 21 colour bands, interpolating linearly, regardless of the actual number of bands selected. This is to improve the colour resolution of plots. As a consequence colours are also interpolated within these 21 bands from the #levels set here. Thus defining more contour levels will give finer control over the colours used in shaded-image plots.
Note 4:	Whichever way they are defined, contour bands must be in ascending, monotonic order. This is particularly significant for USER_DEFINED mode: you will not be permitted to create bands that have zero or negative intervals.

Number format : Controlling the number format of contour values

By default D3PLOT tries to work out a sensible number format to display the contour values in. In some cases the user may want to change the default behavior and this can be achieved here.

You can select either 'Scientific', 'General' or 'Manual' to control how the numbers are formatted.

The number of decimal places used can be set for 'Scientific' and 'General' formats.

For the 'Manual' format both the number of decimal places and the exponent value can be set.

Automatic Transparency

The Automatic Transparency option can be used to automatically set the transparency of entities based on the data values being plotted on them.

In complex plots it is often difficult to locate minimum and maximum values as they are often hidden behind other entities. Although entities can be blanked to reveal these "hidden" parts this is sometimes unsatisfactory as a solution.

By varying the transparency of entities it is possible to view these minimum and maximum values while still viewing the whole structure.

This option affects the transparency of entities in SI, CT and CL plots.

Transparency Ramp

These options control how the transparency levels are calculated for the data values being plotted.

Magnitude

Transparency of entities is scaled by the magnitude of the data values.

Min -> Max

Transparency is scaled from the minimum data value (clear) to the maximum (opaque).

Max -> Min

Transparency is scaled from the maximum data value (clear) to the minimum (opaque).

Order

This option controls the shape of the transparency ramp. Order 1 generates a linear ramp using the data value (X), order 2 generates a ramp based on (X ²), order 3 uses (X ³) and order 4 used (X ⁴)

Default SI plot

SI plot with default automatic transparency options

SI plot with transparency scaled from Min ->Max

These options control the minimum and maximum transparency values that are used when calculating the transparency ramp.

The values must lie in the range 0 (clear) to 100 (opaque).

A separate transparency value can also be defined that is used for all items that are not being contoured.

SI plot with transparency scaled from Min ->Max and a minimum transparency value of 30

SI plot with transparency scaled from Min ->Ma and uncontoured items set to 100 (opaque)

Special options for FORMABILITY

If the data component is set to FORMABILITY (in the Metal Forming category) then the Contour Levels menu is replaced with the options opposite, for more details see METAL FORMING.

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