Playback

With this final step you will generate the ground truth (e.g. semantic segmentation and depth maps, normal maps, stereo pairs, and also instance segmentation, etc.) of your recorded sequence. First of all you need to convert your recordings stored as .txt files in the RecordedSequences folder to .json files compatible with the playback process.

Convert recorded sequences to JSON

Go to ROXTracker located in the World Outliner panel in the UE4 editor and search for JSON Management (see Figure 1).

Figure 1. Convert recorded sequences to JSON.

Set the Input Scene TXT File Name and also the Output Scene Json File Name and click on Generate Sequence Json. Json files will be stored in the RecordedSequences folder.

Configure playback process

Go to ROXTracker located in the World Outliner panel in the UE4 editor and search for Playback (see Figure 2).

Figure 2. Configurable parameters for the playback process.

Proceed with the following steps:

• Specify JSON files: add JSON file names to the Json File Names array.
• Start from a given frame: if playback process was accidentally interrupted you can resume the process indicating the latest generated frame (Default: 0).
• Select the desired data to generate: check the desired options you want to generate. You can also choose RGB data format.
• Path: choose where to save the data. Screenshots Save Directory and Screenshots Folder parameters.
• Data resolution: choose generated data resolution (Default: 1920x1080).

Run playback process

In order to proceed with the playback process, you will need to uncheck Record mode from the general ROXTracker configuration (see Figure 1 from Recording section). Run project in the Selected Viewport mode [1]. All the data will be saved by default on GeneratedSequences folder located in the root of UnrealROX project.

[1]	If your main purpose is to generate data and you run the project in VR Preview mode, UnrealROX wouldn’t work properly.