Response to the reviews
**Weakness 1**: Thanks for your insightful comment. Though naively adding random internet videos can potentially introduce noise or bias, we have demonstrated in the experiments that by selecting tourism videos captured at diverse geo-locations and time, GIM can effectively generalize to various zero-shot inputs, e.g., images from different domains and BEV point clouds. As we discuss in the response to all reviewers, we have trained another model with 100h of data showing that GIM scales well with more video data.
In terms of other diverse datasets, we focus on internet videos since they are arguably the most accessible and scalable data source. This ensures that the performance improvement of GIM can be reproduced by almost anyone on any future architecture. However, the key to the generalization of GIM is the data diversity and scale, rather than the source of the videos. Hence, we expect that as long as the dataset is **diverse** and **large**, it will work with GIM. So for example, adding proprietary videos captured in various environments, will likely further boost performance.
We will clarify the importance of our video selection strategy and the key to the generalization of GIM in the camera-ready paper.
**Weakness 2**: We completely agree that preventing overfitting is crucial. Specifically, overfitting can happen if the training videos are not diverse enough and biased towards certain types of scenes. An effective and implicit regularization that is applied in GIM is the selection of video data. We achieve this by selecting video data from diverse geo-locations and scene conditions; we focus on YouTube tourism videos and describe our search and filter strategies in Sec. 3 of the paper. Please refer to Table 6 of the paper for detailed statistics of the selected videos. Another potential factor in preventing overfitting is the amount of data. The continually growing amount and diversity of internet videos effectively reduces the risk of overfitting. We also added strong data augmentations during GIM training to make the model resistance to noise. Our experimental results in the zero-shot evaluation benchmark (ZEB) demonstrate the effectiveness of this implicit regularization approach.
Finally, though never used in our video selection process, evaluating the trained model on the ZEB benchmark can also verify whether a set of candidate videos are potentially biased or noisy.
We will include the above answers in camera-ready paper and hope they sufficiently address your concerns.
**Weakness 3**: For the selection of internet videos, our recommendation is to choose videos with high resolution, clear images, long duration and small number of scene transitions. To ensure these points, we choose tourism videos. They are generally 0.5-2 hours long, with a person holding the camera and recording his/her travel, mostly without transitions. GIM also has some robustness to transitions in the video since drastic changes from one frame to another make it very difficult for matches to survive after robust fitting. Even if a few matches survive, it is very difficult for the label propagation to continue. Finally, GIM includes strong data augmentations during training, which introduces noise to make the model more resistant to various sources of error in the input data.
We will include the above answer in camera-ready paper.
**Question 1**: As mentioned in the answer of weakness 1, we did not randomly download videos from the internet. Instead, as mentioned in Sec. 3 of the main paper, we selectively used tourism videos for training. The selected tourism videos are usually captured by a person traveling around various places. Even only on YouTube, we can find tourism videos spanning thousands of hours and covering various regions, years, times, weather conditions, and lighting. These videos are not limited to a single type of scene; they include diverse activities like walking, cycling, driving and more. This ensures the data diversity and minimizes the bias.
Based on your suggestion, we will describe our video selection process and its effectiveness in details in our camera-ready paper. The code will also be released upon acceptance.
**Question 2**: Please refer to the details we have mentioned in weakness 3 for information how we handle noise and varying quality.
Some pre-processing is indeed applied. First, we search YouTube for tourism videos using the keywords 'walk in' or 'walk through', and then downloaded videos that are at least 30 minutes long. Then we remove the first 5 minutes and the last 5 minutes of the video and keep only the middle part, because there may be a quick preview or summary which can contain non-smooth scene transitions. We will include these details in the appendix of camera-ready paper for clarity.
**Question 3**: Please refer to the response of weakness 2.