I haven’t tried it yet, but the following plugin may help achieve something similar to this request:
elias-sundqvist/obsidian-annotator: A plugin for reading and annotating PDFs and EPUBs in obsidian.
An obsidian link to an annotation block-reference will, when clicked, open the corresponding file and scroll to the associated highlight. If the file is already open in a pane, then the link will cause the existing pane to scroll instead.
nice plugin, thank you for sharing. it seems to work based on an online service/component
Yes, Obsidian Annotator looks just like what we need here regarding PDF annotation. It is still not approved as a community plugin, though. Hope to be so in the coming days.
Waiting for approval as community plug-in.
The following issues may be of interest regarding offline usage and privacy maters:
Should be fixed promptly.
Thank you for informing me. The plugin offers a good annotation experience but it doesn’t provide area-highlight function
@Ocarinalover The following plugin supports area highlight, if I understand you correctly:
MarkMindCkm/obsidian-markmind: A mind map, outline and pdf annotate tool for obsidian
Also, it supports committing/saving highlights to the original PDF document.
There is another issue discussing saving comments to the original PDF document.
Same as I thought！
This is quite a good solution, thank you for suggesting this plugin. I have tried it and found it still has space for improvement. and maybe other kinds of solution could be better (maybe not contaminate the vault with lots of text for labeling purposes)
I want to add my support to this request. These functions would be of great help in doing research
This seems to be a great logseq workflow, if I can replicate in Obsidian. There are some workarounds for annotating but block referencing and indentation remain an issue.
This requires that obsidian implements robust URI natively. The plugin Advanced URI does this but this feature must be implemented natively. This is the main reason why I switched to Craft for the time being until the developers implement this.
Nonetheless the obsidian community is a great resource 
A lot of people migrating from Citavi could make the jump once this is implemented. Logseq seems the example to follow.
Would love to see this feature!
Liquid Text recently implemented this. Would be nicer to have something that works within Obsidian without the need to use another app for PDF management
I already made a similar request, however, it never got much attention.
I am at a loss as to why, but it seems there is not enough user demand for this feature to become a core feature. I hope I am proved wrong.
You can use the annotator plugin
+1
I think this feature makes a lot of sense for anyone who works with PDFs. Obsidian allows us to import PDFs, but unlike pictures, PDFs have a lot of pages. It can be hard to make use of information from different pages unless we can organize it according to our notes. In order to better incorporate PDFs into our notes, it would help if we could link specific paragraphs to notes.
simply highlight and annotation of pdf could already be realized by annotation and markmind plugin
