(02-08-2023, 05:48 PM)rich2005 Wrote: Well, Gimp is a raster (bitmap) editor not a CAD program and is not really meant for such purpose, although sometimes can be used.Rich,
Quote:The coordinates of a fixed point in a drawing change after i use the move tool to move the drawing around so i can see other features and then return to the fixed point.
Does this mean that that there is more than one layer coming from the scan, such as a multi-page PDF or Tif ?
..or have you added the scan to an existing image. Always better if you can give a screenshot of the problem.
If it is a layer over some other layer, no need to move it. Turn the layer visibility off. The layer eye icon in the layer dock.
Quote:1) when an image is loaded into GIMP, the coordinate system of GIMP is aligned with the scanned data of the image.
Very-very unlikely, Although you can set a CAD origin anywhere in a drawing it is usually bottom and left so that co-ordinates remain positive.
Gimp on the other hand being a raster graphic program uses top left for the canvas origin. You can move layers and selections outside the canvas area and increase canvas size to accommodate the change but then the canvas origin is reassigned to top left
Quote:2) Using the GIMP Move tool, the tool moves only the viewer, not the drawing and its coordinate system.
The Gimp move tool will move the active layer to a new position on the Gimp canvas The canvas still has 0, 0 top-left
Quote:3) If i quit the drawing without making any changes in it, the coordinates of a fixed point within the image should have the exact same coordinates when the image is opened up once again.
Gimp does not make automatic Saves, if you do not Save as .xcf (or export in other format) then obviously no changes.
First, Thank you for responding.
I experimented more carefully.
Here is what I found. If i open and close a file, the coordinates are maintained between each cycle. The fifth opening results in coordinates
of a point that are exactly the same as the first opening.
Secondly,
If i scale the entire image, so that i do not have to move the image in order to measure two points far apart in the image, then the measurements
are repeatable and the only error is user error, not GIMP error.
Thirdly
If i use scrolling, the measurements are repeatable within user error (+- 2 units).
Forthly
If i use the move tool, in order to measure an image point off the screen, the measurements are not repeatable.
This suggests that the coordinate system is tied to the layer and not to the image. it also suggests that when i use the move tool
it moves the entire image within the layer; hence the coordinates change for a given image feature.
Conclusion:
move tool is NOT the same as scrolling. scrolling moves the viewer and not the image within the layer.
move tool moves the image within the layer and not the viewer's view
am i understanding the above?