Refactor readme (#17)

* Refactor readme

* Add links

* Fix link error

* add table caption

* Refine readme

* Add missing plus

* Be specific of comparison

README.md

@@ -33,13 +33,21 @@ a part of the OpenMMLab project developed by [MMLab](http://mmlab.ie.cuhk.edu.hk
 
 - **Natural integration with 2D detection**
 
-  All the about **300 models, methods of 40+ papers**, and modules supported in [MMDetection](https://github.com/open-mmlab/mmdetection/blob/master/docs/model_zoo.md) can be trained or used in this codebase.
+  All the about **40+ methods, 300+ models**, and modules supported in [MMDetection](https://github.com/open-mmlab/mmdetection/blob/master/docs/model_zoo.md) can be trained or used in this codebase.
 
 - **High efficiency**
 
-  It trains [faster than other codebases](./docs/benchmarks.md).
+  It trains faster than other codebases. The main results are as below. Details can be found in [benchmark.md](./docs/benchmarks.md). We compare the number of samples trained per second (the higher, the better). The models that are not supported by other codebases are marked by `×`.
 
-Apart from MMDetection3D, we also released a library [MMDetection](https://github.com/open-mmlab/mmdetection) and [MMCV](https://github.com/open-mmlab/mmcv) for computer vision research, which are heavily depended on by this toolbox. Like [MMDetection](https://github.com/open-mmlab/mmdetection) and [MMCV](https://github.com/open-mmlab/mmcv), MMDetection3D can also be used as a library to support different projects on top of it.
+  | Methods | MMDetection3D | [OpenPCDet](https://github.com/open-mmlab/OpenPCDet) |[votenet](https://github.com/facebookresearch/votenet)| [Det3D](https://github.com/poodarchu/Det3D) |
+  |:-------:|:-------------:|:---------:|:-----:|:-----:|
+  | VoteNet | 358           | ×         |   77  | ×     |
+  | PointPillars-car| 141           | ×         |   ×  | 140     |
+  | PointPillars-3class| 107           |44     |   ×      | ×    |
+  | SECOND| 40           |30     |   ×      | ×    |
+  | Part-A2| 17           |14     |   ×      | ×    |
+
+Like [MMDetection](https://github.com/open-mmlab/mmdetection) and [MMCV](https://github.com/open-mmlab/mmcv), MMDetection3D can also be used as a library to support different projects on top of it.
 
 ## License
 

docs/benchmarks.md

@@ -13,15 +13,15 @@ with some other open source 3D detection codebases.
 
 ## Main Results
 
-We compare the training speed (samples/s) with other codebases if they implement the similar models. The results are as below, the greater the numbers in the table, the faster of the training process.
+We compare the training speed (samples/s) with other codebases if they implement the similar models. The results are as below, the greater the numbers in the table, the faster of the training process. The models that are not supported by other codebases are marked by `×`.
 
-| Methods | MMDetection3D |votenet| Det3D | OpenPCDet |
-|:-------:|:-------------:|:-----:|:-----:|:---------:|
-| VoteNet | 358           |   77  | ×     | ×         |
-| PointPillars-car| 141           |   ×  | 140     | ×         |
-| PointPillars-3class| 107           |   ×      | ×    |44     |
-| SECOND | 40           |   ×      | ×    |30     |
-| Part-A2| 17           |   ×      | ×    |14     |
+| Methods | MMDetection3D | OpenPCDet |votenet| Det3D |
+|:-------:|:-------------:|:---------:|:-----:|:-----:|
+| VoteNet | 358           | ×         |   77  | ×     |
+| PointPillars-car| 141           | ×         |   ×  | 140     |
+| PointPillars-3class| 107           |44     |   ×      | ×    |
+| SECOND| 40           |30     |   ×      | ×    |
+| Part-A2| 17           |14     |   ×      | ×    |
 
 ## Details of Comparison
 
@@ -197,8 +197,6 @@ We compare the training speed (samples/s) with other codebases if they implement
 
   ```
 
-
-
 ### PointPillars-car
 
 * __MMDetection3D__: With release v0.1.0, run
@@ -258,6 +256,8 @@ We compare the training speed (samples/s) with other codebases if they implement
 
 ### SECOND
 
+For SECOND, we mean the [SECONDv1.5](https://github.com/traveller59/second.pytorch/blob/master/second/configs/all.fhd.config) that was first implemented in [second.Pytorch](https://github.com/traveller59/second.pytorch). Det3D's implementation of SECOND uses its self-implemented Multi-Group Head, so its speed is not compatible with other codebases.
+
 * __MMDetection3D__: With release v0.1.0, run
 
   ```bash