[Qgis-user] How to create a QGIS grid but not the usual way

[Thayer Young]

 Hi John,
You can prevent the warning about no spatial index by creating the index for each layer using the "Create Spatial Index" processing algorithm. Or you can just ignore the warning. 

If you are certain of the EPSG code for your layers you can use the "Assign Projection" processing algorithm. EPSG 2264 sounds like a good candidate. Reprojecting to UTM Zone 17N should be good also EPSG:26917. 
You can find both of these tools by entering their names into the search bar at the bottom left of the main QGIS window or at the top of the Processing Toolbox panel.
If you have roads and county boundary shapefiles in the same EPSG 2264, you should be able to clip your roads (input) with your county boundary (overlay) using the Clip tool. If you want your roads to overlap the county boundary try reprojecting your Extent polygon to 2264.
Another possibility is that there are invalid geometries. You may want to try the Check Validity, Fix Geometries, and or v.clean tools to find and correct invalid geometry.
You may also be able to get more information about what is going wrong from the messages panel. There is a toggle button for it in the bottom right of the main QGIS window.  
You should be able to get a good pdf converter for free or low cost. So you can convert image files and compile them into a single pdf.
-Thayer
PS Please remember to send responses to the entire mailing list. 

   ----- Forwarded Message ----- From: John Antkowiak <john_antkowiak at yahoo.com>To: Thayer Young <thayeray at yahoo.com>Sent: Saturday, May 15, 2021, 11:06:38 PM EDTSubject: Re: How to create a QGIS grid but not the usual way
  Hi, Thayer. I may have to ask for a follow-up explanation. I do apologize. 
I re-projected the file and each layer separately. Now the GUI tells me, as anticipated, that the CRS is EPSG:2264. (Scrolling down through the list of available systems to use, I found this one - which is further identified as NAD83/NC (ftUS) - before I found the UTM choices. So I selected it.) Each layer matches, so that part went as expected.
Then I saved the project and restarted QGIS to rule those variables out when the next step failed. Now when I clip the data to a new shapefile, I see the following error:  
"No spatial index exists for input layer, performance will be severely degraded." 
I received the same error before re-projecting everything. This happens with both layers I'm trying to clip: the county boundary and the streets.
And when I try to add the resulting shapefiles to a new, blank map project, they fail to load. "File unsupported" or words to that effect.
I suspect (but I don't  know) the problem is that I'm trying to clip the two State-government layers against the grid polygons (rectangles) I created, even though I was able to save that layer as a valid shapefile with a recognized CRS matching that of the State layers. 
If I have to use UTM instead, how do I know whether it's Zone 16 or 17? (From my professional experience years ago - I have a decent amount of experience but no formal GIS education so I'm no expert regarding projection systems - I thought I remembered the dividing line between the two being in Florida.)
Alamance County is centered east to west in the northern half of North Carolina.
This step was necessary because I find I can't create an atlas as a PDF and I don't  have Adobe to create one from jpegs. I can export a single map to PDF, but not an atlas unless there's a plugin I can go obtain. So I'm trying to create 9 separate maps by clipping the total extent by the gridlines you helped me create (very effectively I might add - thank you again!)
Again, both thanks and apologies...
- John A.
  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20210516/34cfca50/attachment.html>