Vtk/SimpleCubeTutorial - Revision history

Joel2: /* Related Discussions */

2024-07-09T22:41:25Z

Related Discussions

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	=Related Discussions=		=Related Discussions=
	* [[~~User:Tohline/~~vtk/Understanding#Understanding_vtk_Tools_Inside_VisTrails\|Understanding vtk Tools Inside VisTrails]]		* [[vtk/Understanding#Understanding_vtk_Tools_Inside_VisTrails\|Understanding vtk Tools Inside VisTrails]]
	* [[~~User:Tohline/~~vtk/SimpleCubeTutorial/CubeDetails#Cube_Definition_Details\|Cube Definition Details]]		* [[vtk/SimpleCubeTutorial/CubeDetails#Cube_Definition_Details\|Cube Definition Details]]
	* [[~~User:Tohline/~~vtk/ColorLookupTablea#Color_Lookup_Tables\|Color Lookup Tables]]		* [[vtk/ColorLookupTablea#Color_Lookup_Tables\|Color Lookup Tables]]
	* [http://www.bu.edu/tech/files/2010/10/VTK-Fall-2010.ppt Robert Putnam's (Boston University) powerpoint tutorial] -- includes a ''Structured_Points'' example, written in Simple Legacy Format		* [http://www.bu.edu/tech/files/2010/10/VTK-Fall-2010.ppt Robert Putnam's (Boston University) powerpoint tutorial] -- includes a ''Structured_Points'' example, written in Simple Legacy Format

Joel2: /* XML-Formatted */

2024-07-09T22:40:51Z

XML-Formatted

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	==XML-Formatted==		==XML-Formatted==
	* [[~~User:Tohline/~~vtk/Examples/XMLwarpedQuilt#Example_Input_Files_.26_VisTrails_Pipelines\|Warped Quilt]]: Uses vtk<font color="orange">XML</font><font color="red">PolyData</font>Reader, vtkWarpScalar, & vtk<font color="orange">XML</font><font color="red">PolyData</font>Mapper		* [[vtk/Examples/XMLwarpedQuilt#Example_Input_Files_.26_VisTrails_Pipelines\|Warped Quilt]]: Uses vtk<font color="orange">XML</font><font color="red">PolyData</font>Reader, vtkWarpScalar, & vtk<font color="orange">XML</font><font color="red">PolyData</font>Mapper
	* Rectilinear Grid: Uses vtk<font color="orange">XML</font><font color="red">RectilinearGrid</font>Reader, vtkWarpScalar, & vtk<font color="orange">XML</font><font color="red">DataSet</font>Mapper		* Rectilinear Grid: Uses vtk<font color="orange">XML</font><font color="red">RectilinearGrid</font>Reader, vtkWarpScalar, & vtk<font color="orange">XML</font><font color="red">DataSet</font>Mapper
	** [[~~User:Tohline/~~vtk/Examples/XMLRectilinearGrid#XML_.28RectilinearGrid.29_Warped_Quilt_Example\|Warped Quilt]] (6 x 6 grid)		** [[vtk/Examples/XMLRectilinearGrid#XML_.28RectilinearGrid.29_Warped_Quilt_Example\|Warped Quilt]] (6 x 6 grid)
	** [[~~User:Tohline/~~vtk/Examples/XMLRectilinearGrid#XML_.28RectilinearGrid.29_Mexican_Hat_Example\|Mexican Hat]] at two different resolutions: (50 x 50 grid) and (10 x 10 grid); the lower resolution example also illustrates how the '''vtkWarpScalar''' module handles user-specified Normals.		** [[vtk/Examples/XMLRectilinearGrid#XML_.28RectilinearGrid.29_Mexican_Hat_Example\|Mexican Hat]] at two different resolutions: (50 x 50 grid) and (10 x 10 grid); the lower resolution example also illustrates how the '''vtkWarpScalar''' module handles user-specified Normals.

	=Related Discussions=		=Related Discussions=

Joel2: /* Simple Legacy Format */

2024-07-09T22:40:11Z

Simple Legacy Format

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	==Simple Legacy Format==		==Simple Legacy Format==
	* [[~~User:Tohline/~~vtk/Examples/LegacyCubeG#Example_Input_Files_.26_VisTrails_Pipelines\|Cube Example G]]: Uses vtk<font color="red">PolyData</font>Reader & vtk<font color="red">PolyData</font>Mapper		* [[vtk/Examples/LegacyCubeG#Example_Input_Files_.26_VisTrails_Pipelines\|Cube Example G]]: Uses vtk<font color="red">PolyData</font>Reader & vtk<font color="red">PolyData</font>Mapper
	* [[~~User:Tohline/~~vtk/Examples/LegacyBUstructuredPoints\|BU (Robert Putnam) Example of Structured Points]]: Uses vtk<font color="red">StructuredPoints</font>Reader & vtk<font color="red">DataSet</font>Mapper		* [[vtk/Examples/LegacyBUstructuredPoints\|BU (Robert Putnam) Example of Structured Points]]: Uses vtk<font color="red">StructuredPoints</font>Reader & vtk<font color="red">DataSet</font>Mapper
	* [[~~User:Tohline/~~vtk/Examples/LegacyCornellRectGrid\|Cornell Example of Rectilinear Grid]]: Uses vtk<font color="red">RectilinearGrid</font>Reader & vtk<font color="red">DataSet</font>Mapper		* [[vtk/Examples/LegacyCornellRectGrid\|Cornell Example of Rectilinear Grid]]: Uses vtk<font color="red">RectilinearGrid</font>Reader & vtk<font color="red">DataSet</font>Mapper

	==XML-Formatted==		==XML-Formatted==

Joel2: /* Overview */

2024-07-09T22:36:31Z

Overview

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	<font color="blue">'''General Explanation:''' </font>		<font color="blue">'''General Explanation:''' </font>
	* The "Piece" of the "PolyData" being described in this file contains 8 points and 6 polygons (polys). The substantive information is provided by "Data Arrays" located within three subsections of the file: ''CellData,'' ''Points,'' and ''Polys.''		* The "Piece" of the "PolyData" being described in this file contains 8 points and 6 polygons (polys). The substantive information is provided by "Data Arrays" located within three subsections of the file: ''CellData,'' ''Points,'' and ''Polys.''
	* Points: This ''DataArray'' provides the same information as [[~~User:Tohline/~~vtk/SimpleCubeTutorial/CubeDetails#Specifying_the_location_of_the_cube.27s_corners.2Fvertices\|the ''POINTS'' subsection of a ''Simple Legacy Formatted'' data file]], that is, it specifies the <math>~(x, y, z)</math> coordinates of the eight points (vertices) of our simple cube. The header of this ''DataArray'' tells the VTK Reader that it should read 3 numbers (the coordinates) at a time, and that the (space-delimited) data should be read as 32-bit floating-point numbers. The Reader will expect this ''DataArray'' to contain <font face="Courier">(NumberOfPoints x NumberOfComponents =) 24</font> separate floating-point numbers.		* Points: This ''DataArray'' provides the same information as [[vtk/SimpleCubeTutorial/CubeDetails#Specifying_the_location_of_the_cube.27s_corners.2Fvertices\|the ''POINTS'' subsection of a ''Simple Legacy Formatted'' data file]], that is, it specifies the <math>~(x, y, z)</math> coordinates of the eight points (vertices) of our simple cube. The header of this ''DataArray'' tells the VTK Reader that it should read 3 numbers (the coordinates) at a time, and that the (space-delimited) data should be read as 32-bit floating-point numbers. The Reader will expect this ''DataArray'' to contain <font face="Courier">(NumberOfPoints x NumberOfComponents =) 24</font> separate floating-point numbers.
	* Polys: In combination with one another, the two ''DataArrays'' found between the ''Polys'' metatags provide the same information as [[~~User:Tohline/~~vtk/SimpleCubeTutorial/CubeDetails#Defining_the_cube.27s_six_quadrilateral_faces\|the ''POLYGONS'' subsection of a ''Simple Legacy Formatted'' data file]]. The first ''DataArray,'' whose Name is "connectivity," identifies the group of POINTS that should be connected to define the complete perimeter of each face of the cube; the second ''DataArray,'' whose Name is "offsets," tells the Reader how many integers in the "connectivity" array should be skipped in order to begin defining each subsequent polygon. In other words, the number of POINTS that define the perimeter of each polygon — in this case, 4 for every polygon — is given by the ''difference'' between successive ''offsets.''		* Polys: In combination with one another, the two ''DataArrays'' found between the ''Polys'' metatags provide the same information as [[vtk/SimpleCubeTutorial/CubeDetails#Defining_the_cube.27s_six_quadrilateral_faces\|the ''POLYGONS'' subsection of a ''Simple Legacy Formatted'' data file]]. The first ''DataArray,'' whose Name is "connectivity," identifies the group of POINTS that should be connected to define the complete perimeter of each face of the cube; the second ''DataArray,'' whose Name is "offsets," tells the Reader how many integers in the "connectivity" array should be skipped in order to begin defining each subsequent polygon. In other words, the number of POINTS that define the perimeter of each polygon — in this case, 4 for every polygon — is given by the ''difference'' between successive ''offsets.''
	* CellData: The first ''DataArray,'' whose name is "cell_scalars," assigns a scalar value to each polygon, i.e., to each face of the cube; the Reader will expect this ''DataArray'' to contain <font face="Courier">(NumberOfPolys =) 6</font> separate 32-bit floating-point numbers. The second ''DataArray,'' whose name is "cell_normals," specifies the <math>~(x, y, z)</math> coordinates of the tip of the unit vector that defines the NORMAL to the surface of each polygon, as [[~~User:Tohline/~~vtk/SimpleCubeTutorial#Assigning_NORMALS_to_POLYGONS\|explained in the discussion, above]]; the Reader will expect this ''DataArray'' to contain <font face="Courier">(NumberOfPolys x NumberOfComponents =) 18</font> separate 32-bit floating-point numbers.		* CellData: The first ''DataArray,'' whose name is "cell_scalars," assigns a scalar value to each polygon, i.e., to each face of the cube; the Reader will expect this ''DataArray'' to contain <font face="Courier">(NumberOfPolys =) 6</font> separate 32-bit floating-point numbers. The second ''DataArray,'' whose name is "cell_normals," specifies the <math>~(x, y, z)</math> coordinates of the tip of the unit vector that defines the NORMAL to the surface of each polygon, as [[vtk/SimpleCubeTutorial#Assigning_NORMALS_to_POLYGONS\|explained in the discussion, above]]; the Reader will expect this ''DataArray'' to contain <font face="Courier">(NumberOfPolys x NumberOfComponents =) 18</font> separate 32-bit floating-point numbers.


	[[Image:XMLreaderPipeline.png\|right\|thumb\|250px\|Pipeline02]]<font color="blue">'''XMLPolyDataReader:''' </font>		[[Image:XMLreaderPipeline.png\|right\|thumb\|250px\|Pipeline02]]<font color="blue">'''XMLPolyDataReader:''' </font>
	The figure labeled [[~~User:Tohline/~~vtk/SimpleCubeTutorial#Reading_Cube_Model_from_a_Web_Site\|"Pipeline01" near the top of this page]], shows the VisTrails pipeline that we used to construct and render a ''simple cube'' based on a web-accessible input file that provides data in a ''Simple Legacy Format.'' That input data was fed into the VisTrails pipeline using the ''vtkPolyDataReader'' module. As is illustrated by the "Pipeline02" figure, shown here on the right, the equivalent XML-formatted data file — which, as noted immediately above, is accessible on the web as a file named ''XMLformattedSimpleCube.vtp'' — can be fed into the VisTrails pipeline using the ''vtkXMLPolyDataReader'' module.		The figure labeled [[vtk/SimpleCubeTutorial#Reading_Cube_Model_from_a_Web_Site\|"Pipeline01" near the top of this page]], shows the VisTrails pipeline that we used to construct and render a ''simple cube'' based on a web-accessible input file that provides data in a ''Simple Legacy Format.'' That input data was fed into the VisTrails pipeline using the ''vtkPolyDataReader'' module. As is illustrated by the "Pipeline02" figure, shown here on the right, the equivalent XML-formatted data file — which, as noted immediately above, is accessible on the web as a file named ''XMLformattedSimpleCube.vtp'' — can be fed into the VisTrails pipeline using the ''vtkXMLPolyDataReader'' module.

	<font color="blue">'''No Color Table:''' </font>		<font color="blue">'''No Color Table:''' </font>

Joel2: /* Assigning NORMALS to POLYGONS */

2024-07-09T22:33:40Z

Assigning NORMALS to POLYGONS

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	===Assigning NORMALS to POLYGONS===		===Assigning NORMALS to POLYGONS===

	[[Image:CubeDetails.png\|right\|thumb\|250px\|caption\|Annotated Cube]] In [[~~User:Tohline/~~vtk/SimpleCubeTutorial/CubeDetails#Cube_Definition_Details\|an accompanying presentation]] (which includes a larger image of the ''Annotated Cube'' shown here, on the right), we explain how VTK's ''Simple Legacy Format'' reader identifies (and internally catalogs) the unit vector that points perpendicular to — and, hence, that defines the normal of — each POLYGON. Here, after highlighting the key points of this [[~~User:Tohline/~~vtk/SimpleCubeTutorial/CubeDetails#Cube_Definition_Details\|more detailed presentation]], we illustrate how different definitions of the polygon NORMALS can be specified by inserting additional lines of data into the input data file.		[[Image:CubeDetails.png\|right\|thumb\|250px\|caption\|Annotated Cube]] In [[vtk/SimpleCubeTutorial/CubeDetails#Cube_Definition_Details\|an accompanying presentation]] (which includes a larger image of the ''Annotated Cube'' shown here, on the right), we explain how VTK's ''Simple Legacy Format'' reader identifies (and internally catalogs) the unit vector that points perpendicular to — and, hence, that defines the normal of — each POLYGON. Here, after highlighting the key points of this [[vtk/SimpleCubeTutorial/CubeDetails#Cube_Definition_Details\|more detailed presentation]], we illustrate how different definitions of the polygon NORMALS can be specified by inserting additional lines of data into the input data file.

	<font color="blue">Default Assignment:</font>		<font color="blue">Default Assignment:</font>

Joel2: /* Other Knobs to Twist */

2024-07-09T22:29:44Z

Other Knobs to Twist

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	<font color="blue">Use vtkLookupTable Module:</font>		<font color="blue">Use vtkLookupTable Module:</font>
	* You can construct a wide range of different color Lookup Tables by adding the "vtkLookupTable" module to the VisTrails pipeline. In an [[~~User:Tohline/~~vtk/ColorLookupTablea#Color_Lookup_Tables\|accompanying presentation]], we explain and illustrate how this is done.		* You can construct a wide range of different color Lookup Tables by adding the "vtkLookupTable" module to the VisTrails pipeline. In an [[vtk/ColorLookupTablea#Color_Lookup_Tables\|accompanying presentation]], we explain and illustrate how this is done.

	<font color="blue">Wireframe:</font>		<font color="blue">Wireframe:</font>

Joel2: /* Specifying Colors of Cell Faces via a User-defined Color Table */

2024-07-09T22:28:05Z

Specifying Colors of Cell Faces via a User-defined Color Table

← Older revision		Revision as of 18:28, 9 July 2024
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	===Specifying Colors of Cell Faces via a User-defined Color Table===		===Specifying Colors of Cell Faces via a User-defined Color Table===
	Now, suppose you don't like the colors that are assigned to each of the six faces of the cube by [[~~User:Tohline/~~vtk/SimpleCubeTutorial#Deciphering_VTK.27s_default_Lookup_Table\|VTK's ''default'' color table]]. You can assign a different set of colors by explicitly defining your own "LOOKUP_TABLE." To illustrate how this is done, we have added nine additional lines of ASCII text to the input data files shown in ''Example D'' and ''Example E'', below. In both cases, we have inserted the LOOKUP_TABLE that has been provided as part of the "simple cube" example that is provided on pp. 331-332 of the [http://www.kitware.com/products/books/vtkguide.html ''VTK User's Guide''].		Now, suppose you don't like the colors that are assigned to each of the six faces of the cube by [[vtk/SimpleCubeTutorial#Deciphering_VTK.27s_default_Lookup_Table\|VTK's ''default'' color table]]. You can assign a different set of colors by explicitly defining your own "LOOKUP_TABLE." To illustrate how this is done, we have added nine additional lines of ASCII text to the input data files shown in ''Example D'' and ''Example E'', below. In both cases, we have inserted the LOOKUP_TABLE that has been provided as part of the "simple cube" example that is provided on pp. 331-332 of the [http://www.kitware.com/products/books/vtkguide.html ''VTK User's Guide''].

	<div align="center">		<div align="center">
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	<tr>		<tr>
	<td align="center">		<td align="center">
	[[Image:Screenshot02.~~png~~\|200px\|Screenshot_A]]		[[Image:Screenshot02.jpg\|200px\|Screenshot_A]]
	</td>		</td>
	<td align="center" valign="bottom">		<td align="center" valign="bottom">

Joel2: /* Deciphering VTK's default Lookup Table */

2024-07-09T22:21:18Z

Deciphering VTK's default Lookup Table

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	Eventually I discovered documentation that defines the default settings for VTK's color maps. In §6.6 of [http://www.amazon.com/Visualization-Toolkit-Object-Oriented-Approach-Graphics/dp/193093419X/ref=pd_sim_sbs_b_1?ie=UTF8&refRID=0EFGPTSBP5E136WEK4V7 Schroeder, Martin, & Lorensen (2006)] (see specifically the subsection titled '''Color Maps''' on p. 196), we are told the default settings are established via a specification of HSV (Hue-Saturation-Value) rather than via an <font face="Courier">rgb</font> specification. The default settings are: HueRange (0, 2/3); SaturationRange (1,1); and ValueRange (1,1). This terminology is explained in an [[~~User:Tohline/~~vtk/ColorLookupTablea#Color_Lookup_Tables\|accompanying presentation]].		Eventually I discovered documentation that defines the default settings for VTK's color maps. In §6.6 of [http://www.amazon.com/Visualization-Toolkit-Object-Oriented-Approach-Graphics/dp/193093419X/ref=pd_sim_sbs_b_1?ie=UTF8&refRID=0EFGPTSBP5E136WEK4V7 Schroeder, Martin, & Lorensen (2006)] (see specifically the subsection titled '''Color Maps''' on p. 196), we are told the default settings are established via a specification of HSV (Hue-Saturation-Value) rather than via an <font face="Courier">rgb</font> specification. The default settings are: HueRange (0, 2/3); SaturationRange (1,1); and ValueRange (1,1). This terminology is explained in an [[vtk/ColorLookupTablea#Color_Lookup_Tables\|accompanying presentation]].

	===Specifying Colors of Cell Faces via a User-defined Color Table===		===Specifying Colors of Cell Faces via a User-defined Color Table===

Joel2: /* Specifying Colors of Cell Faces Using a Default Color Table */

2024-07-09T22:20:30Z

Specifying Colors of Cell Faces Using a Default Color Table

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	<td align="center">		<td align="center">
	[[Image:Screenshot02.~~png~~\|200px\|Screenshot_A]]		[[Image:Screenshot02.jpg\|200px\|Screenshot_A]]
	</td>		</td>
	<td align="center" valign="bottom">		<td align="center" valign="bottom">
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	* "CELL_DATA 6" means that the subsequent numerical values should be assigned, in sequence, to each of the 6 polygonal (square) faces of the cube.		* "CELL_DATA 6" means that the subsequent numerical values should be assigned, in sequence, to each of the 6 polygonal (square) faces of the cube.
	* "SCALARS cell_scalars float 1" (see Examples A & B) means that, in each case, the assigned numerical value will be a floating-point number; "SCALARS cell_scalars int 1" (see Example C) means that the assigned numerical value will be an integer number. As necessary, the name "cell_scalars" will be used to reference this assigned set of scalar values. In principle, up to four separate sets of scalar values can be assigned to the faces of the cube (see the discussion associated with the parameter ''numComp'' on p. 329 of the [http://www.kitware.com/products/books/vtkguide.html ''VTK User's Guide'']); the "1" at the end of this line of text indicates that the values associated with the name "cell_scalars" will be referenced as the ''first'' scalar component; it is optional if there is only one scalar component.		* "SCALARS cell_scalars float 1" (see Examples A & B) means that, in each case, the assigned numerical value will be a floating-point number; "SCALARS cell_scalars int 1" (see Example C) means that the assigned numerical value will be an integer number. As necessary, the name "cell_scalars" will be used to reference this assigned set of scalar values. In principle, up to four separate sets of scalar values can be assigned to the faces of the cube (see the discussion associated with the parameter ''numComp'' on p. 329 of the [http://www.kitware.com/products/books/vtkguide.html ''VTK User's Guide'']); the "1" at the end of this line of text indicates that the values associated with the name "cell_scalars" will be referenced as the ''first'' scalar component; it is optional if there is only one scalar component.
	* "LOOKUP_TABLE default" means that the color that is assigned to each face will be determined by correlating the scalar value assigned to each face with the scalar values assigned to the standard rainbow of colors as defined by [[~~User:Tohline/~~vtk/SimpleCubeTutorial#Deciphering_VTK.27s_default_Lookup_Table\|VTK's ''default'' lookup color table]].		* "LOOKUP_TABLE default" means that the color that is assigned to each face will be determined by correlating the scalar value assigned to each face with the scalar values assigned to the standard rainbow of colors as defined by [[vtk/SimpleCubeTutorial#Deciphering_VTK.27s_default_Lookup_Table\|VTK's ''default'' lookup color table]].

	<font color="blue">Example A:</font>		<font color="blue">Example A:</font>
	* The six assigned floating-point numbers range from 0.0 to 1.0, in increments of 0.2. By inspection, it appears as though [[~~User:Tohline/~~vtk/SimpleCubeTutorial#Deciphering_VTK.27s_default_Lookup_Table\|VTK's default color table]] spreads the rainbow of (RGB) colors across this same interval, with 0.0 being assigned to red and 1.0 being assigned to blue. It is therefore not surprising that the three initially visible faces of the rendered cube are red, green, and blue. The colors of the other three faces of the cube are revealed by using the computer mouse to spin the VisTrails spreadsheet rendering of the cube.		* The six assigned floating-point numbers range from 0.0 to 1.0, in increments of 0.2. By inspection, it appears as though [[vtk/SimpleCubeTutorial#Deciphering_VTK.27s_default_Lookup_Table\|VTK's default color table]] spreads the rainbow of (RGB) colors across this same interval, with 0.0 being assigned to red and 1.0 being assigned to blue. It is therefore not surprising that the three initially visible faces of the rendered cube are red, green, and blue. The colors of the other three faces of the cube are revealed by using the computer mouse to spin the VisTrails spreadsheet rendering of the cube.

	<font color="blue">Example B:</font>		<font color="blue">Example B:</font>
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	<font color="blue">Example C:</font>		<font color="blue">Example C:</font>
	* The six assigned integer numbers range from 0 to 5, in increments of 1. One face — the one whose assigned scalar value is zero — is colored red; all five other faces are colored blue because the color table does not extend beyond 1.0 and VTK's default coloring rule (see [[~~User:Tohline/~~vtk/SimpleCubeTutorial#mapping\|further elaboration, below]]) is to peg scalar values at one (i.e., blue) if their assigned values are greater than unity.		* The six assigned integer numbers range from 0 to 5, in increments of 1. One face — the one whose assigned scalar value is zero — is colored red; all five other faces are colored blue because the color table does not extend beyond 1.0 and VTK's default coloring rule (see [[vtk/SimpleCubeTutorial#mapping\|further elaboration, below]]) is to peg scalar values at one (i.e., blue) if their assigned values are greater than unity.

	<font color="red">'''Comment#1 (by J. E. Tohline):'''</font> Notice that, once a set of scalar values has been assigned to cell faces, the colors provided by the default LOOKUP_TABLE override the "tomato" color that is specified by the "vtkProperty" module of the VisTrails pipeline. The default "tomato" color can be retrieved without modifying the new input datafile by clicking on (i.e., selecting) the "vtkPolyDataMapper" module in the VisTrails pipeline, dragging the "ScalarVisibilityOff" method into the "Set Methods" segment of the VisTrials Builder Window, then reexecuting the pipeline.		<font color="red">'''Comment#1 (by J. E. Tohline):'''</font> Notice that, once a set of scalar values has been assigned to cell faces, the colors provided by the default LOOKUP_TABLE override the "tomato" color that is specified by the "vtkProperty" module of the VisTrails pipeline. The default "tomato" color can be retrieved without modifying the new input datafile by clicking on (i.e., selecting) the "vtkPolyDataMapper" module in the VisTrails pipeline, dragging the "ScalarVisibilityOff" method into the "Set Methods" segment of the VisTrials Builder Window, then reexecuting the pipeline.

Joel2: /* Minimalistic Cube */

2024-07-09T22:01:12Z

Minimalistic Cube

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	==Minimalistic Cube==		==Minimalistic Cube==
	In the above example, the vertices and polygons that were used to describe the underlying wireframe model of the cylinder were defined inside the "vtkCylinderSource" method in a manner that is hidden from the user. (Although, see [[~~User:Tohline/~~vtk/Understanding#Understanding_vtk_Tools_Inside_VisTrails\|our more detailed accompanying discussion]].) Similarly, the VisTrails library contains methods that can be used to draw a cube (vtkCubeSource), a sphere (vtkSphereSource), or a Cone (vtkConeSource). (As further practice, you may want to insert these other standard building block models into the VisTrails pipeline in place of, or in addition to, the CylinderSource.) In general, however, a user of VisTrails will want to supply her/his own data model. Here, we use the structure of a simple cube to illustrate one straightforward method of providing model data in the ''Simple Legacy Format'', which VisTrails — and, more generally, all of the vtk library modules — will understand.		In the above example, the vertices and polygons that were used to describe the underlying wireframe model of the cylinder were defined inside the "vtkCylinderSource" method in a manner that is hidden from the user. (Although, see [[vtk/Understanding#Understanding_vtk_Tools_Inside_VisTrails\|our more detailed accompanying discussion]].) Similarly, the VisTrails library contains methods that can be used to draw a cube (vtkCubeSource), a sphere (vtkSphereSource), or a Cone (vtkConeSource). (As further practice, you may want to insert these other standard building block models into the VisTrails pipeline in place of, or in addition to, the CylinderSource.) In general, however, a user of VisTrails will want to supply her/his own data model. Here, we use the structure of a simple cube to illustrate one straightforward method of providing model data in the ''Simple Legacy Format'', which VisTrails — and, more generally, all of the vtk library modules — will understand.

	===Reading Cube Model from a Web Site===		===Reading Cube Model from a Web Site===
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	<td align="left" colspan="2">		<td align="left" colspan="2">
	The sets of numbers used to define the POINTS & POLYGONS of this simple cube are [[~~User:Tohline/~~vtk/SimpleCubeTutorial/CubeDetails\|explained here]].		The sets of numbers used to define the POINTS & POLYGONS of this simple cube are [[vtk/SimpleCubeTutorial/CubeDetails\|explained here]].
	</td>		</td>
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	</div>		</div>

	6. In an [[~~User:Tohline/~~vtk/SimpleCubeTutorial/CubeDetails\|accompanying discussion]], we explain how to interpret — and, therefore, also how to modify as desired — the rows and columns of numbers that have been used here to define the POINTS (vertices) and POLYGONS of a simple cube.		6. In an [[vtk/SimpleCubeTutorial/CubeDetails\|accompanying discussion]], we explain how to interpret — and, therefore, also how to modify as desired — the rows and columns of numbers that have been used here to define the POINTS (vertices) and POLYGONS of a simple cube.

	7. For fun, use VisTrails' "HTTPFile" module to load each of the following files that provide ASCII data written in VTK's Simple Legacy Format to specify a more intricate multi-polygonal structure. I found these posted on [http://people.sc.fsu.edu/~jburkardt/data/vtk/vtk.html J. Burkardt's FSU website]:		7. For fun, use VisTrails' "HTTPFile" module to load each of the following files that provide ASCII data written in VTK's Simple Legacy Format to specify a more intricate multi-polygonal structure. I found these posted on [http://people.sc.fsu.edu/~jburkardt/data/vtk/vtk.html J. Burkardt's FSU website]: