Results Viewer

Visualise and analyse your PIV vector fields. The Results Viewer is the central hub for inspecting velocity data, calculating statistics, transforming coordinates, and merging multi-camera fields.

Central Hub for Post-Processing

After running PIV processing, the Results Viewer lets you explore your data and perform additional operations. Choose your data source, select variables to visualise, and access powerful post-processing features.

View

Visualise any variable

Transform

Rotate, flip, scale

Merge

Combine cameras

Statistics

Mean & turbulence

Overview

The Results Viewer displays PIV vector fields as colour-mapped images with interactive controls. It supports multiple data sources including calibrated and uncalibrated results, ensemble averages, merged multi-camera fields, and computed statistics.

GUI Features

  • Interactive frame-by-frame navigation
  • Adjustable colour limits and colormaps
  • Real-time cursor coordinate display
  • Magnifier tool for zoomed inspection
  • Corner coordinates display button
  • One-click image download and copy

Post-Processing

  • Geometric transforms (rotate, flip, scale)
  • Multi-camera field merging
  • Mean and turbulence statistics
  • Reynolds stress tensor computation
  • Vortex detection (gamma criteria)

Data Types & Operations

Different data sources have different capabilities. The table below shows which operations are available for each data type. Understanding these restrictions is essential for planning your post-processing workflow.

Data SourceViewTransformsCoordinatesMergeStatistics
Uncalibrated Instantaneous----
Uncalibrated Ensemble----
Calibrated Instantaneous*
Calibrated Ensemble----
Merged Instantaneous-
Merged Ensemble----
Stereo Instantaneous†---
Stereo Ensemble----
Mean Statistics----
Merged Statistics----
Stereo Statistics----

* Merge requires 2+ cameras and planar (2D) data only. Stereo setups with a uz component cannot be merged.

† Stereo data includes the out-of-plane velocity component (uz). Statistics can be computed but transforms and merging are not supported.

Uncalibrated Data

Uncalibrated results can only be viewed. Transforms, merging, and statistics require calibrated data with physical coordinates. Run calibration first to enable these features.

Stereo (3D) Merging

Merging is blocked for stereo PIV data. When a uz component is detected, the merge button will be disabled. Stereo calibration combines both cameras automatically.

Ensemble Data

Ensemble results are already time-averaged across all frames, so per-frame operations (transforms, statistics calculation) are not applicable. View ensemble data directly to see the mean velocity field from your ensemble PIV processing.

Viewing Controls

The viewer provides intuitive controls for customising how your data is displayed. Adjust colour limits, choose colormaps, and navigate through frames to explore your results.

Colormap Selection

Choose from multiple colormaps to best visualise your data. Different colormaps are suited to different types of data and analysis goals.

default
viridis
plasma
inferno
magma
cividis
jet
gray

Colour Limits

Set upper and lower limits for the colour scale. Use "Auto-Calculate" to automatically determine appropriate limits based on your data range.

Lower Limit: Minimum value (saturates below)

Upper Limit: Maximum value (saturates above)

Leave blank for automatic scaling per frame.

Frame Navigation

For instantaneous data, use the frame slider or arrow buttons to navigate through your time series. The playback feature animates through frames at adjustable speeds.

Frame Slider

Drag to any frame

Arrow Buttons

Step forward/back

Playback

0.5 to 10 FPS

Axis Limits & Plot Title

Customise the plot display with specific X and Y axis limits and a custom title. Leave blank for automatic axis scaling based on your coordinate data.

X Min: auto
X Max: auto
Y Min: auto
Y Max: auto

Variable Selection

The variable dropdown provides access to all available fields organised by category. Variables are grouped based on their source and calculation type for easy navigation.

Instantaneous Variables

Raw velocity components from frame files. Available for all data sources.

uxHorizontal velocity component
uyVertical velocity component
uzOut-of-plane velocity (stereo only)

Calculated Statistics

Derived quantities from statistics calculation. Requires running the statistics processor.

Mean ux/uyTime-averaged velocities
TKETurbulent kinetic energy
uu, vv, uvReynolds stress tensor
vorticityOut-of-plane vorticity

Variable Naming Convention

Variables are prefixed to indicate their source. The viewer automatically filters available variables based on your selected data source.

inst:Instantaneous frame data
inst_stat:Per-frame calculated stats
mean:Time-averaged statistics
ens:Ensemble-averaged results

Special Variable Labels

Some variables use mathematical notation for clarity in the dropdown:

u'u'

uu Reynolds stress

v'v'

vv Reynolds stress

u'v'

uv Reynolds stress

TKE

Turbulent kinetic energy

omega

Vorticity

div u

Divergence

gamma1

Gamma 1 vortex criterion

gamma2

Gamma 2 vortex criterion

Configuration

The Results Viewer and all post-processing operations are configured throughconfig.yaml. The GUI automatically updates this file when you change settings.

GUI vs CLI Processing

Understanding the difference between GUI and CLI usage is important for batch processing:

GUI Mode
  • - Processes one base_path at a time
  • - Interactive visualisation and controls
  • - Select path via dropdown
  • - Ideal for exploration and setup
CLI Mode
  • - Processes ALL active_paths in config
  • - Batch processing without interaction
  • - Configure once, run on many datasets
  • - Ideal for production workflows
video: base_path_idx: 0 # Which base path to use (0-indexed) camera: 1 # Camera number to view data_source: calibrated # calibrated or uncalibrated variable: ux # Variable to display run: 1 # Run number for multi-run files piv_type: instantaneous # instantaneous or ensemble cmap: viridis # Colormap name lower: '' # Lower colour limit (blank = auto) upper: '' # Upper colour limit (blank = auto)

Batch Processing Note

When using CLI commands for transforms, merging, or statistics, the operations will run on all paths listed in active_paths. Configure your datasets first using the GUI, then run batch processing via CLI for efficiency.

Post-Processing Features

The Results Viewer provides access to three powerful post-processing modules. Each feature has its own detailed documentation page with complete workflows and examples.

Transforms

Rotate, flip, and scale your vector fields. Essential for aligning multi-camera setups before merging.

  • - Geometric: rotate, flip
  • - Scale velocities & coordinates
  • - Swap/invert components
Learn More

Merging

Combine vector fields from multiple cameras into a single seamless field using Hanning window blending.

  • - Requires 2+ cameras
  • - Automatic overlap detection
  • - Distance-based weighting
Learn More

Statistics

Calculate mean velocities, Reynolds stresses, TKE, and turbulence quantities across your time series.

  • - Mean & instantaneous stats
  • - Reynolds stress tensor
  • - Vortex detection (gamma)
Learn More

Next: Transform Your Data

Ready to align your camera views? Learn how to rotate, flip, and scale your vector fields to prepare for merging or correct orientation issues.

Continue to Transforms