How to specify pixel/mm AND total page size on BMP export?
Posted: Fri Nov 03, 2017 9:53 pm
First let me explain what I am trying to do, and the forum can tell me how to proceed, perhaps with the use of an add-on.
I have a set of Draw documents in which I have carefully placed geometric shapes, all specified in mm, inside a Page whose ruler is in mm also. At the end I want to have this rendered to a bitmap of 50 pixel/mm. Now before folks start commenting on the input specifications of commercial printers, etc., let me say that this bitmap is to be used by a CNC manufacturing machine to produce a cut piece of sheet plastic that conforms to the bitmap, and the machine simply reads in the bitmap; in fact, the BMP header specifies resolution in pixels per meter. And I am not even interested in that being written into the file as I can pop that in with a binary file viewer app directly. And the bitmap only needs 1 bit per pixel and "1" indicates that the material exists whereas "0" indicates not. At this point I have the drawing as having the viewable colors as either White of Grey 5.
When I try to export, the dialog gives controls for the resolution and page size, but a change in one causes the other to change, seemingly to keep the total # of pixels for the page to be some preset amount. I suppose I could do the ridiculous thing and increase the size of the page so as to get more pixels, but at the point, I don't even know the formula. When the dialog comes up, it initially says the height & width is 500.00 mm each (which is what I had set it to), and then 37 pixels per cm; when I change the resolution to 500 pixels/cm, it changes the height & width to 37.8 mm, meaning that it's screwy even with that! What I would like for that dialog to allow me to do is specify the 500 mm in height & width AND the resolution as 500 pixels/cm.
EDIT: OK, I trying increasing the size to 3000 x 3000 mm (the maximum, it seems),and then when I tried to export, it gave me the errors: "Graphics Filter not found" & "Error saving the document".
I have a set of Draw documents in which I have carefully placed geometric shapes, all specified in mm, inside a Page whose ruler is in mm also. At the end I want to have this rendered to a bitmap of 50 pixel/mm. Now before folks start commenting on the input specifications of commercial printers, etc., let me say that this bitmap is to be used by a CNC manufacturing machine to produce a cut piece of sheet plastic that conforms to the bitmap, and the machine simply reads in the bitmap; in fact, the BMP header specifies resolution in pixels per meter. And I am not even interested in that being written into the file as I can pop that in with a binary file viewer app directly. And the bitmap only needs 1 bit per pixel and "1" indicates that the material exists whereas "0" indicates not. At this point I have the drawing as having the viewable colors as either White of Grey 5.
When I try to export, the dialog gives controls for the resolution and page size, but a change in one causes the other to change, seemingly to keep the total # of pixels for the page to be some preset amount. I suppose I could do the ridiculous thing and increase the size of the page so as to get more pixels, but at the point, I don't even know the formula. When the dialog comes up, it initially says the height & width is 500.00 mm each (which is what I had set it to), and then 37 pixels per cm; when I change the resolution to 500 pixels/cm, it changes the height & width to 37.8 mm, meaning that it's screwy even with that! What I would like for that dialog to allow me to do is specify the 500 mm in height & width AND the resolution as 500 pixels/cm.
EDIT: OK, I trying increasing the size to 3000 x 3000 mm (the maximum, it seems),and then when I tried to export, it gave me the errors: "Graphics Filter not found" & "Error saving the document".