[Qgis-user] Output to pdf file doesn't contain vector details

[Michael Edward McNeil]

I'm an almost total novice with regard to GIS in general and QGIS in particular. Nonetheless I've been attempting to put together a test map (using data I will make use of, in part) utilizing the contour lines for the island of Great Britain – obtaining data in that regard from the space shuttle's worldwide Shuttle Radar Topography Mission (SRTM).

I obtained the data and loaded it into QGIS, no problem. After extracting the contours, the lines shown in QGIS are nice and sharp, and vectorize properly when zooming in and out. I'm using 100 meters between lines (rather than the default 10 m) which means that in some regions of the planet, they're not all that dense; nonetheless if you're looking at a larger scale view of, say, Wales or Scotland, the contour lines show up at that scale as generally pretty dense. The solution, of course, using vector graphics is to zoom in, then you can see the full detail.

Anyway, things are fine while still within QGIS (except for the secondary issue noted below). However, I wanted to output the vectorized contour lines into a file I could input into (e.g.) CorelDRAW to add other layers and do the graphical finishing touches on the desired map. I tried svg format – got the message about svg handling in QGIS being buggy – and indeed the svg output didn't seem to work.

So, I tried pdf. What I get there (out of an 80 GB resulting pdf file!) is simply solid color – not distinguishable contour lines – in regions where the lines would otherwise (at a larger scale) be dense. I told the output Layout page that it should vectorize all output – but zooming in doesn't help. (I recall that my svg format experiment also similarly produced solid color and lacked contour detail.)

What am I doing wrong?

A secondary issue, by the way, is that I apparently can't see the data after I save my QGIS project, close and re-enter the app. After re-entering QGIS the Layers pane shows all the layers, all properly check-marked for visibility, just like before, but nothing shows up in the display window – it's totally blank white. So… I'm surviving by never (or seldom – then reloading the data) leaving the app. But, what's going on?

I'm running QGIS v. 3.32.2-Lima under MacOS 12.6.8.

Thanks, all.

Best,
Michael McNeil