Alignment of Vector Grid

[Johanna Botman]

I am creating a map of an area that is about 40km x 40km and want to use a grid to help determine the location of roads (- see my previous question).

When I created the grid I used the tools under Vector, I find that my grid is not quite north south aligned. I've not noticed this when I've made grids over smaller distances, but in this case it is really obvious. It causes aesthetic issues when I go to Composer and create my map, especially if I want to have a frame around my map.

I've tried rotating the grid (I made it as a polygon layer) but am not having much joy. If I use the Advanced Digitising tools, I don't have enough control to rotate the alignment the 0.5 degrees or so that I need. I've tried an Affine Transform but have had no success with that either.

Is there a way to create the vector grid so that it is 'perfectly' north south (so it aligns with the edge of the map or paper)?

Johanna

[Ramon Andiñach]

In the composer if you select the map and look in Item Properties, there's a check box for Show Grid. Expand that and that should help. 

-ramon.

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[Bill Williamson]

Is the grid labelled?

[Johanna Botman]

Thanks Ramon,

I know about the Show Grid feature and I would be happy to use it. BUT, I needed a grid, initially so that I could locate each of the roads and assign them a grid value. That's why I created my own grid first.

I was happy to then use the Show Grid on the composer - overlayed to my grid - because I like the zebra style. That's where I first noticed that the grid that I created is not 'straight' with the page or the composer grid.

The consequence of this is that my road locations are not correct in the bottom right hand corner of the map because of the skew of my grid compared with the Show Grid. Does that make sense?

[Johanna Botman]

Bill,  What do you mean? My grid?

 

[Bill Williamson]

Hi Joanna,

Maybe a hybrid workaround is to create a layer which shows no style but does show the label according to your street index grid. Then use the composer grid. No doubt there will be some rotation offset between the layer of labels and the composer grid but if it is not great it may not be noticeable.
But as you say there is too much skew.

As far as the advanced digitising tools, maybe two things
 - select the target, but then with no button pressed move the mouse some distance away before the click and hold. This provides "more leverage" and finer control.
 - explore the snapping options to select a lower or nil tolerance.

hth

[Nyall Dawson]

Hey Johanna,

Can you post your CRS and extents of the grid? I'll have a play.

Nyall

[Johanna Botman]

I have emailed you the grid files. I am working in MGA94 Zone 55

Johanna

[Andrew Jeffrey]

Hi Johanna,

It's not a re-projection issue is it?

I created a grid the way you described above using EPSG:28355 for my project and source datasets, but I am not seeing the rotation issue you described.

I was able to recreate something similar to what you described when re-projecting map layers on the fly to fit the project CRS. For example if I create my grid off a dataset using EPSG:28355, then set my project to EPSG:4283 - I then see rotation similar to what you described.

Andrew

On Wednesday, 30 July 2014 15:41:40 UTC+10, Johanna Botman wrote:

[Johanna Botman]

Thanks for having a look, Andrew.

All our work is done in Zone 55, so I'm not sure that it is a reprojection issue.  But my underlying data is in a .tab file and now I'm wondering if that is causing an issue. I'll have a look around to see what I can find out.

Johanna