Home Computer graphics In latest computer vision research, Waymo researchers propose Block-NeRF: a method that reconstructs arbitrarily large environments using NeRF

In latest computer vision research, Waymo researchers propose Block-NeRF: a method that reconstructs arbitrarily large environments using NeRF

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Source: https://arxiv.org/pdf/2202.05263.pdf

Neural rendering is a big step forward in the quest to create photorealistic multimedia content. Neural rendering is connected to traditional computer graphics and incorporates principles for building algorithms to synthesize visuals from real-world data. Recent advances in this discipline have made it possible to develop new views from many photos taken with cameras. Although not a new concept, previous research has focused on small-scale, object-centric reconstruction. It should be noted that due to the limited capacity of the model, expanding to city-wide areas may result in unwanted artifacts and poor visual quality.

Researchers from UC Berkeley, Waymo, and Google Research have proposed a grid-based Block-NeRF variant to model dramatically larger parameters, taking NeRFs to the next level. The neural radiation domain is a simple, densely integrated network (weight less than 5 MB) trained to replicate input images of a particular scene using rendering loss.

Reconstructing city-scale settings is essential for high-impact use cases such as autonomous driving and aerial surveys, as is widely known. However, it has certain limitations and difficulties. There are several issues of model capacity, memory, and computational limits, so the bottlenecks don’t end there. In addition, training for such large areas is unlikely to be gathered in one shot under constant conditions. Managing transitory elements (cars and pedestrians) and changing weather and lighting conditions is one of the challenges this undertaking presents.

The research team offers some solutions to the problems. One of them is to divide huge environments into a series of Block-NeRFs. These segments would be trained independently in parallel before being displayed. At inference time, they are interactively concatenated. As a result, the approach can add more Block-NeRF to the environment or update existing blocks without retraining the entire environment.

NerFs and mip-NerFs are the foundations of Block-NerF. mip-NeRF is a newly announced dynamic approach for anti-aliasing neural radiation patterns. This eliminates aliasing issues that degrade NeRF performance in settings when input images are taken from various perspectives. From millions of photos, the suggested Block-NeRF can recreate a consequent and coherent environment by combining many NeRFs.

The research team used San Francisco’s Alamo Square neighborhood as a target location and the Mission Bay district as a baseline for their analysis. Their training dataset consisted of 2,818,745 training images produced from 13.4 hours of driving time collected from 1,330 separate data collection cycles. A table was created that shows the functionality of mip-NerF and the effect of removing individual components from the technique.

Essentially, the research team split a city-wide scenario into many smaller-capacity models, reducing the overall computing cost. Transient objects can be handled efficiently by the suggested Block-NeRF approach, which filters them out during training using a segmentation algorithm. The researchers believe their findings will spur further study into large-scale scene restoration using state-of-the-art neural rendering techniques.

Project: https://waymo.com/research/block-nerf/

Article: https://arxiv.org/pdf/2202.05263.pdf