View and Compare Multiple 3D Data Sets

Applies to: 3D/Studio. For XY data see View and Compare Multiple 2D Data Sets, whose controls this procedure deliberately mirrors.

This option renders many XYZ data nodes together, each in its own pane, tiled across one window. It is the three-dimensional counterpart of the 2D comparison, and it takes a different form for a simple reason: curves can be stacked in one graph and read as a series, but surfaces cannot. Two surfaces drawn in the same axes hide one another. So each node keeps its own pane, its own axes and its own scaling, and the comparison is made by eye across the tiling.

The procedure is for visualization only. No data are altered and nothing is added to the notebook.

Opening the Comparison

· View menu > View First 25 3D Data Nodes renders the first 25 three-dimensional data nodes in the notebook.

· Right-click a data source in the Explorer and choose View and Compare N 3D Data Nodes, where N is the number of XYZ data nodes that source holds.

The right-click item appears only when the source holds more than one such node. Up to 25 nodes are rendered; the window tiles them to fit, so the number across a row depends on how many there are.

Comparing Fits and Other Objects

The same tiled comparison is available one level down, for the fitted or processed children of a data node. Right-click a data source and the menu offers a compare for each kind of child it holds, with a live count: 3D Spline Fits, 3D Non-Parametric Fits, Surface Fits, Loess Smooths, Gridded Smoothings, Sparse Grid Fills, Uniform Grid Interpolations, Saved Data Views, Sectioned Data Sets and Calculations. Each opens one pane per child node, sharing the Format, Normalization and Adjustments controls described below -- with one exception: for a Saved Data Views comparison, the saved look is itself part of the node, so each pane restores its own presentation rather than taking the comparison's common settings.

3D Review Comparisons

Inside the 3D Surface-Fit Review, Compare Selected Surfaces, Compare Selected Residuals and Compare Selected SNPs apply this same tiled comparison to fits and their residuals rather than to data. They are reached from the Review window itself, not from the Explorer.

The Panes

Each pane is a complete, independent rendering of one data node:

· Its own scaling. Every pane is scaled to its own data, so each surface fills its box whatever its z range. This is what makes shapes comparable across panes, and it is also the caution: two panes that look alike may differ by orders of magnitude. Read the z axes -- or use a normalization, below, to put every node on one footing.

· Its own title, taken from the node, above the pane.

· Its own view angles, shown beneath the pane as XYangle and Zangle, so the orientation of every pane is visible at a glance.

· Its own data points, drawn on the surface.

Display Format -- Applied to Every Pane

The Format group selects the display format, and each choice acts on all panes at once. The graph toolbar carries the same three buttons, so either can be used:

· Contour -- every pane becomes a two-dimensional colour contour. This is the most compact form for comparing shapes, and the easiest to read when many nodes are tiled.

· 3D Gradient -- surfaces coloured by a gradient.

· 3D Shaded -- surfaces lit by a light source, which shows relief more strongly.

In this comparison the format is common to every pane, because the panes hold raw data nodes and a data node carries no format of its own -- the comparison is between the data, so the presentation is held common. The colour gradient, the data overlay and the gradient legend are likewise set for the group from the toolbar.

This differs in the comparisons of fitted and processed nodes, above. Those nodes each remember the format they were saved in, and their panes open in it -- so such a comparison can open with some panes as gradients and others as shaded surfaces or contours. Choosing in the Format group there still sets all of them at once.

Selecting Panes

With several nodes tiled it is often useful to set some aside and look at the rest larger.

· Right-click a pane and choose Select this Data Set. The pane is framed to show it is marked. Repeat on as many panes as you wish; the item reads Unselect this Data Set on a pane already marked.

· A selection is only a mark until you act on it. Right-click again and choose Plot > Only Selected Data Sets to redraw the window with the marked panes alone, or Plot > Only this Data Set for the one under the pointer.

· The same menu item then reads Plot All Data Sets, which restores the full tiling.

· Double-clicking a pane plots that pane alone, and double-clicking again restores them all -- the quick route when there is only one pane you want to see larger.

· If a pane has been zoomed, the menu also carries Restore Scaling -- Undo Zoom.

Selection is offered only when more than one node is being compared; with a single data set there is nothing to select against, and the menu is not built unless a pane has been zoomed.

Animation

In the 3D formats the surfaces can be rotated continuously, and all panes animate together, holding the same viewpoint as they turn. Use Modify 3D Animation Settings in the toolbar to set the angular steps and scope, and Start/Stop Animation to run it. Click a surface to pause and click again to resume. Other options are disabled while an animation is running. Set the angular step to suit your display: large steps turn quickly and coarsely, small steps give a smoother rotation.

Wheel and Middle Button

In the 3D formats, wheel up and down changes the Z elevation and a tilt wheel left and right changes the XY rotation. Hold Shift to swap which angle the wheel drives, on mice without a tilt wheel, and Ctrl for coarse 10-degree steps. A middle click restores the default viewpoint. Precision touchpads send the same messages, so two-finger gestures behave identically. The wheel drives all panes at once, and the panes stay synchronized during animation.

In the Contour format the wheel zooms about the cursor instead, and moving the pointer off the graph restores the view as it was before the wheel was used.

Normalization

Surfaces recorded on different scales cannot be compared as they stand. The Normalization group rescales every node before drawing, and because each pane is drawn to its own data, the effect is to put every surface on the same footing:

· None compares the data directly, with no adjustment.

· Unit Volume scales each node so that the volume under its surface is 1.0. Use this when the surfaces represent distributions and their shapes matter more than their magnitudes. The volume is integrated over the node's own x and y extent, cell by cell. This option requires every node in the comparison to be on a rectangular x,y grid; with scattered data the option is unavailable and appears greyed.

· Unit Magnitude scales each node so that its z values run from 0 to 1. Use this to compare shape when the nodes differ greatly in size.

The original data are never modified, and the choice affects the plots only.

Adjustments

Force Zmin=0 holds the bottom of the z scale at zero rather than at the lowest value present, in every pane. TableCurve's gradients are built to show a very dark colour at a true zero baseline; with a small negative minimum that distinction is lost. Clearing the box returns each pane to the limits its own data imply.

What the 2D Comparison Has and This One Does Not

These entries of the 2D comparison are absent here, and for the same reason: they all depend on the data sets sharing one plot. Identification names a trace among many under the pointer; Single Plot and Single/Contour draw every set on common axes. Surfaces cannot be overlaid that way, so each node keeps its pane -- and pane selection, which the 2D comparison has no use for, takes their place here.

OK and Cancel

OK saves the current graph configuration -- format, normalization, adjustments and view settings -- as the default the next time this comparison is invoked. Cancel closes the window without saving; nothing from this session is remembered. Neither produces a notebook item, since the procedure is for visualization only.