I am no expert on this, your best bet is to get help from Sarah Battersby / Kent Marten.
Also, your desired image appears quite tiny so I can't see what's going on, but I am going to take a guess.
Anyways, I want to share with you a couple of things I have done that may help. I think the primary hurdle is that Tableau has no inbuilt support for Raster files (I could be wrong here but I'm sure someone here will correct me).
The easiest way to get the desired result in my case was to get a geo-referenced jpeg (also reduces the workbook size, which may or may not be a concern. It was for me since I was going to render it on the web).
When you export from QGIS as an image, you can see the box co-ordinates:
Now when you add this as an image background you can specify the same co-ordinated with respect to the ones you are using in your workbook.
Once you have that set, the point should line up nicely.
I hope that helps a little.
I believe what you're suggesting is essentially the same as what I've been doing.
The only difference is that in order to get LAT and LONG coordinates that make sense for Tableau (in CRS: 4326) I first need to do a geometry transformation. Otherwise the LAT and LONG measures that I get are literally out of this world (given my 27700 projection) ! see below.
Let's see how we can grow the knowledge of this link of tableau with Shapefiles....
Watch this space
Thank you Kent Marten
I did not know about those spatial functions in Tableau.
I gave it a go and although the geometry seems correct before including the basemap, as soon as I put the basemap something (in the scale) seems to go off.
I've created a simplified file that includes the points and would be happy for anyone to give it a go and let me know it they manage to align both things.
It's a fun exercise but I cannot think about many more ways around. I think I've tried it all !
test_geometry.twbx 354.3 KB
You need to extract the data before sharing?
When I open your workbook it's prompting me to connect to a postgresql database.
You can tell I'm still relatively new to all this..
I did extract the data now and I hope the image also comes as part of the package but I still include it in case you need to recreate the background map.
Its coordinates are :
LEFT : -7.558773300
RIGHT : -7.558003441
I genuinely appreciate your help. I'm trying to convince my whole team to use tableau and if I cannot make a strong case with this example I'm building I might having to end up on this battle !
I'm going to leave this here.
I managed to solve the issue, finally!
I did so many things that I cannot remember what exactly got me there.
But according to what I'm seeing I exported the X and Y coordinates in its original coordinate system (27700) and I also extracted the extents of the base plan in the same coordinate system (st_extent). input X and Y as long and lat in Tableau and imported the basemap as an image.
It all sounds like what I had been doing for a long time but somehow this time it worked. I'm still skeptical but I'll have to replicate it in several other projects and to I'll be able to confirm.
Thank you all for your help.
Thanks for sharing Greg.
I'm glad you got it figured out.