Papers › An Analysis of Scale Invariance in Object Detection - SNIP

An Analysis of Scale Invariance in Object Detection - SNIP

22 Nov 2017arXiv:1711.08189archive 2025-07-28

Bharat Singh, Larry S. Davis

An analysis of different techniques for recognizing and detecting objects under extreme scale variation is presented. Scale specific and scale invariant design of detectors are compared by training them with different configurations of input data. By evaluating the performance of different network architectures for classifying small objects on ImageNet, we show that CNNs are not robust to changes in scale. Based on this analysis, we propose to train and test detectors on the same scales of an image-pyramid. Since small and large objects are difficult to recognize at smaller and larger scales respectively, we present a novel training scheme called Scale Normalization for Image Pyramids (SNIP) which selectively back-propagates the gradients of object instances of different sizes as a function of the image scale. On the COCO dataset, our single model performance is 45.7% and an ensemble of 3 networks obtains an mAP of 48.3%. We use off-the-shelf ImageNet-1000 pre-trained models and only train with bounding box supervision. Our submission won the Best Student Entry in the COCO 2017 challenge. Code will be made available at \url{http://bit.ly/2yXVg4c}.

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Tasks

ObjectObject Detectionobject-detection

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Object Detection COCO test-dev D-RFCN + SNIP (DPN-98 with flip, multi-scale) AP50 67.3 #137 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (DPN-98 with flip, multi-scale) AP75 51.1 #137 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (DPN-98 with flip, multi-scale) APL 57.1 #137 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (DPN-98 with flip, multi-scale) APM 48.8 #137 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (DPN-98 with flip, multi-scale) APS 29.3 #137 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (DPN-98 with flip, multi-scale) box mAP 45.7 #137 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (ResNet-101, multi-scale) AP50 65.5 #159 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (ResNet-101, multi-scale) AP75 48.4 #159 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (ResNet-101, multi-scale) APL 54.9 #159 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (ResNet-101, multi-scale) APM 46.5 #159 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (ResNet-101, multi-scale) APS 27.2 #159 of 225 Archive leaderboard report
Object Detection COCO test-dev D-RFCN + SNIP (ResNet-101, multi-scale) box mAP 43.4 #159 of 225 Archive leaderboard report

Ranks are positions in the archive's leaderboards as they stood at the 2025-07-28 snapshot. Results published since then are not among these rows, so a rank here is not a current standing.

Methods

Introduced by this paper: SNIP

1x1 ConvolutionAverage PoolingBatch NormalizationBottleneck Residual BlockConcatenated Skip ConnectionConvolutionDPNDPN BlockDeformable ConvolutionDense ConnectionsGlobal Average PoolingGrouped ConvolutionKaiming InitializationMax PoolingPosition-Sensitive RoI PoolingR-FCNRPNReLUResidual BlockResidual ConnectionSNIPSoft-NMSSoftmax

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