How to correct the horizon of a timelapse made with Tikee?

Thanks to the wide field of view (220°), the images made by Tikee have a panoramic format. This is why you can sometimes notice “distortions” if you have installed your camera with tilt: some lines that are straight in reality appear curved in the picture.

In this technical blog post, more advanced than the previous ones, we will explore how to correct this horizon line and generate a more aesthetically pleasing timelapse with Tikee..

Technically, our images are projected in an equirectangular format (more info at wikipedia), but as we do not cover a complete sphere, as in a VR video for example, we have trimmed the edges to only present the part that has content .

It may happen that a camera was not installed perfectly horizontally, or that it moved during the shooting, or that the shooting conditions of the subject did not allow to install the camera. camera horizontally.

For these reasons, you may have noticed a sharp curvature of the skyline that may seem disgraceful.

In this technical blog post, we will explore how to correct this horizon line and generate a more aesthetically pleasing timelapse with Tikee.

Why Panoramic Images Can Be Distorted

Technically, our images are projected in an equirectangular format, but since we do not cover a full sphere, we have cropped the edges to show only the content. Sometimes, the camera might not be installed perfectly horizontally, or it may have moved during the shoot, or the shooting conditions might not allow for a perfectly horizontal setup. These situations can cause the horizon line to curve, which can be unsightly.

Necessary Equipment

For this tutorial, you will need:

• Your panoramic photos named in chronological order with an index.

• Adobe Premiere Pro editing software, with its VR plugins.In this technical blog post, more advanced than the previous ones, we will see how to correct this skyline and generate a more aesthetic timelapse.

  
  

Creating the project 

In the example we will take for the rest of the article, the camera installed during the Vivatech 2019 show was oriented downwards to capture the maximum exponents. But, one observes an annoying curvature on the skyline (the windows). In this tutorial, we will straighten this line and crop to focus on the assembly of exhibitors stands.

Our starting workspace

Composition of sequences The fundamental concept that we will use later is “sequence composition”.The principle is that a sequence, in the Adobe Premiere sense, has image size, frame rate, preview, and so on properties. and contains a set of video clips. But a movie can also be seen as a unique video clip that can be integrated into another movie. The latter may have different parameters.Therefore we are going :Integrate our “original” sequence into a larger sequence that will represent a complete equirectangular video (VR 360),Apply a spin VR effect of the sphere to this new sequence,Crop this last sequence,Export the media.

Integration into a complete equirectangular 

The equirectangular format is conventionally used in 360 imagery. It allows to represent a complete sphere: 360 ° horizontally, 180 ° vertically.The Tikee does not capture all this field of view, but only a portion:

To be able to use effects “VR”, it is thus necessary to create a sequence which will have the size of an equirectangular containing the view Tikee: 6960×3480 (to be adapted according to the initial resolution of the sequence with the formula: HEIGHT = ORIGINAL_HEIGHT / 0.441 and WIDTH = 2 * HEIGHT) for a source image of 4260×1534.Let’s start by creating this sequence: Right click in the bin> New element> Sequence.

Creating a sequence

In the settings of the new sequence, enter the required dimensions: 6960×3840 in our case:

Sequence parameters

Rename the sequence to “FullFrame” to be able to distinguish it from the others in the following.We also advise you to save the preconfiguration obtained by clicking on “Save Preset”. We will reuse it later in this tutorial. We called this preconfiguration “Tikee_4260x1534”:

Preconfigurations of sequences

You now have in your bin a new empty sequence named “FullFrame”. Add the “original” sequence by dragging it into the timeline:

You will then have a warning message telling you that the sequences are not the same size. This is what we are looking for, so keep the existing settings.

You now have a new sequence “FullFrame” which corresponds to a complete equirectangular video and contains the images of the Tikee.

Horizon Correction 

Apply the VR Sphere Rotation Effect

We now want to apply an effect from the “Immersive Video” category to this clip. We will then integrate it into a sequence of the same dimension that we will call “FullFrame_horizon”.

You can repeat the first step “Creating a sequence” and select the “Tikee_4260x1534” presets. Name this sequence FullFrame_horizon.

Then add the sequence “FullFrame” by dragging it into the timeline.Now we can add the “Rotation Sphere VR” effect to the “FullFrame” clip of the “FullFrame_horizon” sequence.To do this, select the effect in the “Effects” panel (frame 1 in the following image) and drag it to the “FullFrame” clip in the timeline.You then have this effect that appears in the video effects list of the sequence (frame 2).

Add an effect to a clip

Adjust the Parameters

You can then adjust the “Tilt”, “Pan” and “Ripple” effect settings, which are three angles of the VR sphere, to adjust your horizon.

Adjusted horizon

You will notice in the previous image the presence of a marker to help us to precisely adjust the horizon. To add a marker, click in the preview area of the video, then View> Add Marker.

Add a marker

Once you are satisfied with the settings, you can proceed to the next step.Note: You can use this effect with the timeline to stabilize your time-lapse done with Tikee. Just add key points with different orientations. We will probably come back to this in a future blog post.

Create a Cropping Sequence

Cropping the final video In order to render a video without the black edges, simply create a new “Reframed” sequence with the right dimensions in which we will include the sequence “FullFrame_horizon”.In our case, we want to preserve a panoramic aspect of the same size as an original timelapse made by Tikee. So we create a sequence of size 4620×1534 that we call “Reframed”.

We then obtain the following:

Adjust Position and Scale

It can be noted that there are always black areas. It will be necessary to adjust the position and scale of the clip in the sequence.This is done by modifying the “Position” and “Scale” parameters of the “Path” effect, which is activated by default on all clips in the sequence:

Exporting the Final Sequence

After modifying the “Trajectory” effect Note: this effect is named “Trajectory” because when used with parameters that vary in time, it allows to make a “Pan and Zoom” effect in the video. We will see in a future blog post that it is possible to do even better to move in a timelapse done with Tikee.You now have your final sequence ready to be rendered.

Video obtained: here.

We hope this article was helpful! See you soon for another technical article on timelapses with Tikee.