I am an academic in a field where we explore the performance of materials for a particular application based on just a few metrics. Right now, there is no central repository of this information. My idea was to fix this by building a website that maintains a plot of each metric (potentially from multiple papers) for each material system.
My question is this: a typical article in my field will have a figure with x/y datapoints of the performance metric for the material being studied. I have access to journals through my university and would like to download papers and digitize the datapoints from the figures using a tool such as webplotdigitizer. I would then upload the x/y values (and not the figure or any other content from the paper) into a database. That database would then generate its own figures using a plotting tool and make them available on a website. I would also want to make the data itself available openly for researchers.
Looking online briefly it seems like academic publishers have copyright over the figure itself and not the underlying data. See here and here, for instance. I am also familiar with books that do something close to what I want (something like CRC Handbook of Chemistry and Physics). I also know there are existing online projects that are similar to what I want: the protein data bank, for instance. However, I'm not a lawyer and I don't know if there are special legal requirements to make them work.
Is this reuse of data legal? Should I seriously consider talking to a lawyer before opening it to the public or is it clear cut enough that I won't need to worry.