Changes between Version 32 and Version 33 of VisItBasics
- Timestamp:
- 05/31/11 13:49:39 (14 years ago)
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VisItBasics
v32 v33 64 64 One of the most common and useful plots at our disposal is the ''pseudocolor'' plot, which presents the intensity of a scalar attribute as a color spectrum. In two dimensions, this is fairly straightforward; in three dimensions an additional slice operation (see below) is usually required to get any useful information. 65 65 66 To practice creating pseudocolor plots, we will be using a 2D field 67 66 68 To create a pseudocolor plot: 67 69 68 1. Open a Chombo file or group of Chombo files (see above). 70 1. Enter the command 71 {{{ 72 cp /home/bshroyer/FieldLoopAdvection_2D_documentation_test}}} <home_directory> 73 cd <home_directory>FieldLoopAdvection_documentation_test 74 }}} 75 This copies a 2D field loop advection problem to your home directory and moves into that directory as well. 69 76 70 2. Under {{{Plots}}}, click {{{Add->Pseudocolor->}}}''fieldname''. 77 2. Open a Chombo file or group of Chombo files (see above). 78 79 3. Under {{{Plots}}}, click {{{Add->Pseudocolor->}}}''fieldname''. In the case of the field loop problem, we'll be using the {{{Bx}}} field. 71 80 72 81 [[Image(VisItPseudocolorMenu.png)]] 73 82 74 3. Click the Draw button. This will draw a pseudocolor image in the !VisIt window to the right of the control window. For high-resolution images, this may take several minutes.83 4. Click the Draw button. This will draw a pseudocolor image in the !VisIt window to the right of the control window. For high-resolution images, this may take several minutes. 75 84 76 85 [[Image(Bx2Dscreengrab.png)]] … … 79 88 80 89 [[BR]] 81 == = 3D Plots and the Slice Operator ===90 == 3D Plots and the Slice Operator == 82 91 83 92 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. … … 87 96 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. 88 97 89 To try out a slice operation on a 3D pseudocolor plot :98 To try out a slice operation on a 3D pseudocolor plot on clover: 90 99 91 100 1. Enter the command … … 96 105 This copies a 3D field loop advection problem to your home directory and moves into that directory as well. 97 106 98 1. Create a 3D pseudocolor plot (see"Creating a Pseudocolor Plot" above).107 2. Create a 3D pseudocolor plot (i.e., steps 2-4 "Creating a Pseudocolor Plot" above). 99 108 100 2. Under {{{Plots}}}, select {{{Operators->Slicing-Slice}}}. You have now attached a Slice operator to your plot.109 3. Under {{{Plots}}}, select {{{Operators->Slicing-Slice}}}. You have now attached a Slice operator to your plot. 101 110 102 111 [[Image(SliceOperatorSelect.png)]] 103 112 104 3. In the {{{Plots}}} display, click on the arrow next to your plot to expand it. Then double-click on {{{Slice}}} to open the attributes window.113 4. In the {{{Plots}}} display, click on the arrow next to your plot to expand it. Then double-click on {{{Slice}}} to open the attributes window. 105 114 106 115 [[Image(SliceOperatorApplied.png)]] 107 116 108 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.117 5. 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. 109 118 110 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.119 6. 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. 111 120 112 121 '''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. … … 114 123 [[Image(SliceOperatorAttributes.png)]] 115 124 116 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.125 7. 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. 117 126 118 127 [[Image(Bx3Dsliced.png)]]
