Missing information on text orientation (hOCR property textangle) with LSTM

[stweil]

Tesseract 4 generates the required property textangle with the old OCR engine, not when using LSTM. See ocropus/hocr-tools#148 for examples and more details.

[stweil]

The property should be written here.

[stweil]

@bertsky, the information is missing in the ALTO XML (which has a ROTATION tag) as well.

[bertsky]

Interesting. This should already write the orientation angle (i.e. multiple of 90°) on current master. And it uses PageIterator.Orientation(), which is not related to (legacy) OSD, but the normal page segmentation included in PSM_AUTO, PSM_AUTO_OSD, PSM_AUTO_ONLY and PSM_SPARSE_TEXT_OSD. So it should work with any LSTM model loaded. I wonder why this issue even exists. (Have not tried it myself yet.)

But then, why does the code only use orientation value, but not add the skew angle?

@stweil Sure I'll do the same thing in #2815 as well.

[stweil]

This should already write the orientation angle (i.e. multiple of 90°) on current master.

Indeed, it is fixed in 4.1.1 and master which write the textangle tag, so I close this issue.