Please help me, image as background and have coordinate on it

[motress zlting]

what i need to do is :
1.floor image as background
2.plot the contour on image

but the problem is ....
how to set coordinate in java ? Because im using coordinate to draw the signal strength (green)
i aready have signal data, but it is difficult to draw !
Anyone can help me ?

[Karthik Shiraly]

Do you know the floor plan dimensions in distance units (feet / metres), or the scale factor of the diagram?

[motress zlting]

Karthik Shiraly wrote:Do you know the floor plan dimensions in distance units (feet / metres), or the scale factor of the diagram?

actually i have measure the distance between the access point and the signal strength at distance 12m (green colour), signal is -68dbm

[Karthik Shiraly]

Hi,

I understood the question to be: how to decide the values of {x, y, radius} in pixels, so that Graphics2D.draw(Ellipse2D) can be used.

To translate the radius of 12m into pixel units appropriate to the floor plan picture, you need the dimensions of the floor plan or the scale factor of the picture.

As an example calculation:
Assume the floor plan is on A4 paper (8.27" x 11.69") with a scale 1 inch = 10 feet.
It's digitized at 72 dpi.
So the resulting original image will be 8.27x72=596 pixels by 11.69x72=842 pixels, and 72 pixels represents 10 ft.
Say this image is loaded into your app JPanel (assume the layout is resizable).
At current layout, the JPanel is 400 by 300 pixels.
So the image will be scaled down to fit the JPanel, with scaling factors 400/596 for x-axis, and 300/842 for y-axis.
This means, in the JPanel, 10 feet is represented by (72 x 400/596) pixels on x-axis and (72 x 300/842) pixels on y-axis.
So 12 feet will be represented by (12/10 x 72 x 400/596) pixels on x-axis and (12/10 x 72 x 300/842) pixels on y-axis.

All this is possible only if you knew the floor plan dimensions or knew 1 inch=10feet (or x metres). Without that, it's not possible to translate 12m to pixels.

[motress zlting]

Karthik Shiraly wrote:Hi,

I understood the question to be: how to decide the values of {x, y, radius} in pixels, so that Graphics2D.draw(Ellipse2D) can be used.

To translate the radius of 12m into pixel units appropriate to the floor plan picture, you need the dimensions of the floor plan or the scale factor of the picture.

As an example calculation:
Assume the floor plan is on A4 paper (8.27" x 11.69") with a scale 1 inch = 10 feet.
It's digitized at 72 dpi.
So the resulting original image will be 8.27x72=596 pixels by 11.69x72=842 pixels, and 72 pixels represents 10 ft.
Say this image is loaded into your app JPanel (assume the layout is resizable).
At current layout, the JPanel is 400 by 300 pixels.
So the image will be scaled down to fit the JPanel, with scaling factors 400/596 for x-axis, and 300/842 for y-axis.
This means, in the JPanel, 10 feet is represented by (72 x 400/596) pixels on x-axis and (72 x 300/842) pixels on y-axis.
So 12 feet will be represented by (12/10 x 72 x 400/596) pixels on x-axis and (12/10 x 72 x 300/842) pixels on y-axis.

All this is possible only if you knew the floor plan dimensions or knew 1 inch=10feet (or x metres). Without that, it's not possible to translate 12m to pixels.

Do you know how can i have a layer of coordinate on that image ?

[Karthik Shiraly]

Hi,

Sorry, I didn't understand your question about layer of coordinates. Can you try and explain what you're looking for? Are you asking how to overlay the circle on top of the floor plan so that the floor plan pixels are not overwritten?

[salvin francis]

This is a cross post to https://coderanch.com/t/491417/Java-General/java/plot-this-contour

Admins please note.

[Campbell Ritchie]

salvin francis wrote: . . . Admins please note.

Done.

Hope you don't mind, Robert, Rob and Jesper