Ripples from Ambient Light Interference

Problem

The object shapes appear distorted because of ripples or wave patterns in the point cloud.

Potential causes

Interference from ambient light

The scene is illuminated by strong ambient lighting, which operates on an alternating current (AC) power supply. This light flickers due to the power grid frequency, and the 2D exposure settings are not adjusted to compensate for this frequency. As a result, the ambient light interference introduces ripples or waves in the point cloud.

Interreflections

Ripples in the point cloud may also result from interreflection from the bin wall or nearby objects; see how to deal with Ripples from Interreflections.

Potential solution

Modify capture settings

First, identify the ambient light (grid) frequency in your region.

Open Zivid Studio and connect to your camera. Click on the three dots in the Capture section. Then click Measure scene lighting conditions. The software will display the detected ambient light flicker frequency.

Alternatively, use the SDK method Camera::measureSceneConditions() to measure the ambient light conditions. This method will report whether significant ambient light flicker is detected and if it corresponds to a 50 Hz or 60 Hz power grid.

Use appropriate Presets

If you are using Presets, select the ones tailored for 50 Hz or 60 Hz. These can be found in Zivid Studio or on the Presets（预设值） page.

Adjust settings manually

If you have manually configured settings, ensure your exposure times are synchronized to your region’s grid frequency.

Use sampling rates (exposure times) in the multiples of the grid period in the presence of strong flickering ambient light sources:

• Multiples of 10 000 µs in the presence of 50 Hz grid frequency.

• Multiples of 8 333 µs in the presence of 60 Hz grid frequency.

This method will eliminate ripples in the point cloud, as shown in the image below. Keep in mind that the capture time will likely increase using the settings with exposure times compensated for the grid frequency.

Modify filters

If you cannot afford the increased capture time, consider adjusting the following filters:

• Noise Filter（噪声过滤器） Suppression: Enable this filter and check whether the ripples are removed or reduced.

• Gaussian Smoothing（高斯平滑）: If ripples persist, gradually increase the sigma value until the ripples are removed or sufficiently reduced.

Prevent ambient light

The best way to deal with ambient light is to eliminate it.

Turn off unnecessary light sources near the Zivid camera.

If removing light sources is not possible, block their illumination by using light barriers around the scene. These barriers do not need to be solid; dark curtains or similar materials will suffice.

Change ambient light

If removing ambient light is not feasible, consider using light sources that do not flicker due to AC power supplies.

Choose DC-powered lights such as spotlights or LEDs with a frequency of ≥1 kHz. These will reduce flicker and prevent color inconsistencies in your images.