Deutschland
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Scaling issue for the background image, wrong aspect and size
Dear all, I want to create a 3D model of a house. I've got a CAD plan which was exported to PDF. I want to use it as background image to draw the walls. Therefore I exported it to .png using GIMP.
During import dialog there is just one line which can be used to specify the size of a wall inside the bitmap. I'm missing the possibility to specify x and y of the bitmap to perform an automated resize inside Sweet Home 3D to correct the aspect ratio of such bitmap.
The result of my import was that the background image differs from the walls I draw and specify manually.
I tried to modify the image in PDF and cropped it exactly outside the walls to avoid any white area around the floor plan. Then I resized the picture by ignoring aspect ratio by entering the values of x and y of the house: 888 x 862 pixels.
This picture was again exported to .png format. In import dialog I specified the outer wall = full x size of the bitmap and entered 888 cm. I moved the 0-point to x=12 and y=12 because the walls are 24 cm thick.
The result is still not what I expected. The 0-point is perfect but the x-size and the y-size of the bitmap are smaller than the drawn walls.
It seems that there is a scaling problem or I'm doing something wrong. I put start point and end point of a wall to the exact size of my CAD plan, e.g. start=0 and end=888, distance=888. When I check the y-size I found out that the wall distance of the background image is 845 but it should be 863.
Maybe I'm doing something wrong. So please give me some tips how to do it that every size fits. Thanks a lot.
France
Joined: Nov 7, 2005
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Re: Scaling issue for the background image, wrong aspect and size
As you noticed, there's only one scale factor and pixels are considered as squares. You should try to rescale again your image in GIMP, probably with a factor equal to 863 / 845 = 1.0213 along y.
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Emmanuel Puybaret, Sweet Home 3D creator
Deutschland
Joined: Aug 20, 2020
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Re: Scaling issue for the background image, wrong aspect and size
Thanks for the answer: I scaled it again to 888 / 863 because the CAD drawing contains the walls. It did not help. Then I changed it to 863 / 845 but nothing is changing. The result is still the same. The background image is smaller than the manually created walls but the settings of the walls shows me correct size of each wall. Should I trust the imported background or the wall sizes? I can start from scratch drawing new walls but I'm not sure if the plan will be correct afterwards.
Deutschland
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Re: Scaling issue for the background image, wrong aspect and size
I just noticed that this problem occurs when you connect 2 or more walls. When I create a single wall it fits to the size of the background image. But if I create a second wall and combine them the value inside the distance field shrinks. For example: Wall without connection = 888 cm. Wall with connection to another wall, 90° shifted will reduce the value to 875,9 cm. I learned that I need to work with uncombined walls to have a correct value for the length of the wall.
France
Joined: Nov 7, 2005
Post Count: 9420
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Re: Scaling issue for the background image, wrong aspect and size
Did you see that walls are measured in their middle? You should rather use dimension lines to check the scale of your imported image.
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Emmanuel Puybaret, Sweet Home 3D creator
Deutschland
Joined: Aug 20, 2020
Post Count: 5
Status:
Offline
Re: Scaling issue for the background image, wrong aspect and size
Sorry, I didn't recognize it. When starting drawing the walls the middle seems to be at the end of the wall. When grouping the walls this point changes. I guess that's the reason why I run into trouble. Is there any option to configure a different handling of this point in the middle?
