With the recent update of MapillaryJS, we have made it possible to change the direction and adjust the speed when playing through a sequence. You can now play slower or faster based on your preference, and also play any sequence backwards.

When playing a sequence for inventory purposes, you might want to change the speed depending on the area. Different parts of a sequence can be of higher or lower interest, e.g. a larger road may not contain as many objects of interest as an intersection or suburban area. Increasing the speed also makes it possible to skim through entire sequences very fast.

Playing backwards is desirable when the sequence has been taken looking backwards with respect to the motion. The rearward-facing camera in a rig setup is one such case, but similarly, this applies to 360° camera captures as you pan around the view. Also, playing backwards provides a simple and automatic way of navigating backwards in cases where you're looking to reach the beginning of a sequence instead of its end.

Changing playing speed for regular images and for panoramas

As can be seen in the video above, the spatial navigation arrows are visible when playing with moderate speed and it is then possible to navigate between different sequences while playing.

When increasing speed, the spatial navigation arrows disappear because in that situation it's more relevant to concentrate on the sequence in question than navigate to surrounding ones. It also improves performance, as we avoid loading excess data related to surrounding images. The spatial navigation arrows reappear when you decrease speed or stop playback.

You can try the new features in the example application below by opening the playback controls next to the sequence arrows at the top. You can also use the following keyboard commands when the MapillaryJS viewer is in focus.

• Start or stop playing: Spacebar
• Switch direction when stopped: Shift + D
• Decrease speed: <
• Increase speed: >

Try changing the play direction and speed with the sequence playback controls

Playing with maximum speed requires downloading a fair amount of data and works best on a decent network connection. In many ways, playing through a sequence with high speed is similar to streaming a video. We download a buffer of subsequent images in advance to always keep moving. One difference is that we only have access to certain key frames (the uploaded images) and do smooth 3D transitions between them.

We plan to add more features for easier and faster sequence navigation in future MapillaryJS releases so stay tuned.

/Oscar