Changes between Version 30 and Version 31 of VisItBasics

Timestamp:

05/31/11 12:35:43 (14 years ago)

Author:

Brandon Shroyer

Comment:

—

VisItBasics

@@ -81 +81 @@
 === 3D Plots and the Slice Operator ===
 
-
 Pseudocolor plots are opaque by default.  This means that if you try to create a pseudocolor plot of a 3D dataset, you will get a large colored block.  The boundary conditions of the dataset will be visible, but you will probably want to see some of the interior.  This is where the ''slice operator'' comes in.
 
@@ -88 +87 @@
 The slice operator creates a 2D plot by taking a planar slice of a 3D one.  This is especially effective for problems with some kind of axial symmetry, where a cross section of a coordinate plane will give you a pretty good idea of what's going on throughout the simulation.
 
-To obtain a slice of a 3D pseudocolor plot:
+To try out a slice operation on a 3D pseudocolor plot:
+
+1.  Enter the command 
+{{{
+cp /home/bshroyer/FieldLoopAdvection_documentation_test}}} <home_directory>
+cd <home_directory>FieldLoopAdvection_documentation_test
+}}}
+This copies a 3D field loop advection problem to your home directory and moves into that directory as well.
 
 1.  Create a 3D pseudocolor plot (see "Creating a Pseudocolor Plot" above).
@@ -100 +106 @@
 [[Image(SliceOperatorApplied.png)]]
 
-4.  The {{{Slice 
+4.  Select your intercept option in the {{{Normal}}} box.  This indicates the axis perpendicular to the slice.  Choosing the {{{Z-Axis}}} option, for instance, will create a slice along the {{{xy}}}-plane.
+
+5.  Select the {{{Intercept}}} option in the {{{Origin}}} box.  This indicates the point along your selected axis from which you will start slicing.  For the 3D field loop problem, we will use {{{0.5}}} as an intercept.
+
+ '''Note''':  By default, !VisIt uses 0 as the left boundary of the display.  This means that problems centered on the origin will find their display coordinates shifted; the field loop problem, for instance, has its coordinates changed from {{{[-1, 1], [-.5, .5], [-.5, .5]}}} to {{{[0, 2], [0, 1], [0, 1]}}}.  This is why the intercept is {{{.5}}}--because {{{.5}}} is the new origin for the z-axis.
 
 [[Image(SliceOperatorAttributes.png)]]
+
+6.  Once you have modified your attribute settings to taste, click {{{Apply}}}.  This will apply the slice operator to your 3D pseudocolor plot.  Be aware that the slice operator might not slice ''precisely'' along the designated intercept.  This is because the spatially-valued intercept cannot bisect cells.  When it tries, !VisIt simply rounds up to the nearest whole cell.  This most likely to be a problem on extremely low-resolution problems, but it can cause undue alarm in comparison tests.
+
+[[Image(Bx3Dsliced.png)]]
 
 [[BR]]