1. Introduction
2. LoTSS and the third generation calibration and imaging problem
2.1. Measurement equation formalism
2.2. Direction-independent calibration
2.3. Direction-dependent calibration and imaging
3. Calibration and imaging robustness
3.1. Dynamic range issue
3.2. Regularisation
3.3. Conditioning and solution interval
3.4. Data products
3.5. Comparison between ddf-pipeline-v1 and ddf-pipeline-v2
3.6. ddf-pipeline-v2 robustness and performance
4. LoTSS deep fields data and processing
4.1. Observations
4.2. Image synthesis
4.3. Comparison with deep factor image synthesis
4.4. Cataloguing
5. Conclusion and future plans