Semantic Segmentation of Large-Scale Point Clouds by Encoder-Decoder Shared MLPs with Weighted Focal Loss
Bibliographic record
Abstract
It is essential to do the semantic segmentation task on large-scale outdoor point clouds under the demand of autonomous driving and other applications. Because there is a serious imbalance among different semantic classes, it become a challenging problem. In this paper, we propose a point-based encoder-decoder shared multi- layer perceptrons (MLPs) network with weighted focal loss for semantic segmentation of large-scale point clouds. In the proposed network, we design a residual encoding block which is composed of a relative position encoding block and two neighbor features gathering and combined pooling blocks to aggregate rich neighboring points information. To alleviate the categories imbalance problem, we adopt class-balanced sampler to get the input point cloud block per iteration and use weighted focal loss in the training process. We conducted the experiments on Toronto-3D dataset and the results show that our method achieved an overall accuracy (OA) with 95.70%, a mean intersection over union (mIoU) with 71.85% when input data only contains coordinate information, and an OA with 97.81 %, a mIoU with 81.16% when input data contains both of coordinate and color information.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".