Raster Rotation

tikhpetr

Hi!

I have a raster and a polygon bounding it. Also I built the centroid of the polygon. Tell me, please, how can I rotate the raster around the centroid at a given angle.

Thanks!

DerrickW

If you're just rotating and nothing else, Translation east & north would be 0, scale factor would be 1, rotation angle is your rotation angle and the centroid of your polygon is the X/easting and Y/northing coordinate you need to put in here.

Use this to find your centroid point's X & Y

tikhpetr

DerrickW!

Many thanks! But what do you need to do to get your latest screenshot? In the second screenshot from the bottom of the vector layer menu. How did you switch to it from the raster?

DerrickW

You need to have a feature (point or points) already selected first. Then, right-click in the map window and you'll see the same options.

See the little black dot in my screenshot? The red box around it is your clue that I have that point selected before right-clicking.

DerrickW

You can select all of your points via the layer list, too.

DerrickW

Sorry about the triple-post, but I'm not sure which screenshot you're asking to clarify, I guess.

The very last screenshot in my original post (that shows X & Y coordinates) is the feature info dialogue that I launched by double-clicking on my centroid point. You can also click on this button and then click on your point:

Or view your centroid point's attribute by launching the attribute window from the layer list:

tikhpetr

Hello everybody!

Sorry for not being able to answer for a long time.

And so, I have an aerial photograph. I want to turn it around. I do it like this:

But after applying the tool, the original image flies somewhere! Obviously in the Land of the Happy Hunt.))

Tell me, please, what is my mistake?

https://disk.yandex.ru/d/_BiQ0TzYI6xNVg - this is a data archive if anyone is interested.

Thanks!

DerrickW

Your rotation angle, Rotation Origin (X) and Rotation Origin (Y) are not valid inputs.

Rotation Angle should be a number between 0 and 360. You have "43 30" in there. I'm going to assume you were trying to input Degrees-Minutes-Seconds (DMS). For example: 43° 30' 0". If that's true, you need to convert that value from DMS to decimal-degrees. For example: 43.5

In this example, the yellow dot is the centroid. X & Y are displayed, and I'll use this as my rotation point.

The blue line shows the current bearing of an arbitrary line I'm measuring along: 58.96 degrees

The red line shows where I want it: 89.4 degrees

Difference between them: 30.44 degrees

tikhpetr

DerrickW, many thanks!

One question remains: is it possible to enter the coordinates of the centroid in projection units, for example, in meters?

DerrickW

Yes, if that's what your project's projection is set as. Just make sure to add the coordinates of your centroid after you set the projection.

You should be setting your projection on every project, as soon as you start working.

tikhpetr

Thank you! What a pity that over our continents it is again raining.