train object detection feature extractor with my size!

System information
What is the top-level directory of the model you are using: research/object_detection
Have I written custom code (as opposed to using a stock example script provided in TensorFlow): no
OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Ubuntu 18.04.1
TensorFlow installed from (source or binary): source
TensorFlow version (use command below): 1.14.0
Bazel version (if compiling from source): 0.28.0
CUDA/cuDNN version: 10.0.130/NO
GPU model and memory: Tesla V100-PCIE 16G
Exact command to reproduce:
I followed the tensorflow offical instructions:
Step 1: generate tflite_graph.pb:
cd models/research
python export_tflite_ssd_graph.py
--pipeline_config_path=
--trained_checkpoint_prefix=
--output_directory=
--add_postprocessing_op=

hi, thank you for your nice API:
how can I train feature extractor on coco. for example I need SSD mobileNet v3 640*640 pretrained on coco . how can I achieve this?