Make a ggplot 0,0 XY coordinate to coincide with a specific point of a background image

[paleomariomm]

I have recently came across your package, I am a little excited and skeptical at the same time. I am developing a new package in R and need to solve one important issue. Maybe your knowledge can help me and maybe cooperate in the future. I am going to explain my issue:

I would like to combine two relevant things:

• A ggplot plot.
• And a background image.

However, I would like to do so by taking into consideration a particular point of the background image. I would like a specific point in the background image to be the XY coordinate (0,0) of the ggplot.

Data

Let's start with some data to illustrate what I want. Let's load iris dataset.

data(iris)

We create the ggplot()

Now, let's create this scatterplot with the petal measurements.

g <- ggplot(iris, aes(x= Petal.Length, y = Petal.Width)) + 
  geom_point() +
  xlim(0,7) + ylim(0,2.5) +
  theme_minimal()
print(g)

Background image

This is the background image I would like to implement.

Selecting the XY (0,0) coordinate in the image

This is the point of the background image where I would like to anchor the XY (0,0) of the ggplot.

Expected output

The expected output must be anchoring the XY 0,0 of the ggplot to the selected point of the background image, no matter the size of the image.

It would be something like this:

How can I do it?

[paleomariomm]

This is an example of what I am really developing in my package. It is about human teeth. Not only a fixed point must be selected as the 0,0, but also a rescale of the image is mandatory. But this is for another question. Thanks in advance