Volume scope interrogates volumes to provide visual diagnostic information.

It can be used to visualize Volume Tile Tree data plugged into the volume port in multiple ways. These include flowlines along velocity, the tile tree structure, or numeric values in the volume.

Usage

To use, plug a volume or array of volumes (such as the output of an aero simulation) into the volume plug, and connect the output to an output. Connect a probe_geometry to control where samples are taken. The output is an array of diagnostic geometries which interrogate the volume visually.

Probe Geometry and Volume Sampling

Positions in a volume to interrogate may be provided here in the form of a point-based geometry (Mesh, Points, Strands, Instances). The positions (point_position) of the geometry's points will be used.

If no probe geometry is supplied, a 3D grid of sampling points is automatically constructed. It is controlled with divisions.

The sampler setting controls how the volume is sampled.

Flowline Display

Flowlines are activated using display_flowlines.

Flowlines are strands that start at the sampling positions, and trace the flow through a velocity field. They may be thought of as simulating the path of a particle being advected through the volume. These work together with probe geometry, sampling, culling, and colors. These may be created along voxel_velocity or any other vector property specified with flowline_voxel_property.

As flowlines simulate the path of a particle in a flow, length is controlled by specifying the duration the particle spends in that flow. The parameter flowline_length_in_seconds sets the amount of time in seconds that the particle is advected for. More time in the flow results in longer strands.

flowline_samples_per_second controls the density of samples in time - and functions as a smoothness parameter of the generated curves. At 100 flowline_samples_per_second, a 0.05-second-long flowline will be comprised of 5 samples, and a one second long flowline will have 100. More samples will be smoother and will take more time to compute.

Widths are scaled by flowline_width_scale.

Color

You may remap colors (remap_colors) to the three colors, for high, mid and low values using high_color, mid_color, low_color, based on values from color_voxel_property. Various forms of diagnostics will draw with the values rescaled to these colors. In the case of velocities on flowlines, these represent the distribution of speeds.

Point Display and Numeric Display

Points and numeric display is activated using display_points.

Sample a given property at the sampled locations and create displayable point geometry with the colors as in flowlines. These work together with probe geometry, sampling, culling, and colors.

numeric_display shows the values from numeric_property at the sampled locations numerically.

Points are scaled by point_scale and an optional property specified by size_voxel_property.

Culling

Culling removes samples.

cull_by_property removes any samples that are close to zero in a property specified culling_property. The tolerance is specified with cull_by_property_threshold. For example, you can cull values where fog density is zero.

You may also cull by a culling_bounds_geometry, by supplying a geometry.

Culling may be done by property or by a bounding box.

Multi-res-display

The parameter, display_tile_tree enables a visualization of the multi-resolution volume hierarchy. The deepest n levels (visible_levels) will be shown. These visualizations consist of boxes, and strands outlines. These work together with culling and colors.

The higher-resolution tiles are drawn in the high_color (default red). Then the tiles go to mid_color (default green) for medium-resolution to low_color (default blue) for low-resolution. Keep in mind that the boxes you see are tiles - not voxels. Within each tiles there is a mini-grid of about 5x5x5 actual voxels, depending on the settings of the volume.

This works together with culling geometry and colors.

Thickness of the frames (box outlines) are scaled sing frame_thickness and transparency is controled with tile_transparency.