Foreword
These sheets allow the definition of any geometry by means of a pixel map
An important feature of the procedure used here is that, by choosing one of three sheets, you can specify how to handle the single row of pixels that's all around the periphery of the image.
1)With the first sheet all pixels in the image are kept entirely: this is a normal procedure, but in many cases can give unsafe results. To be used if you know that the pixel map exactly represents the geometry of your section.
2)With the second sheet the row of pixels at the periphery is considered effective only at 50%. This will often give best approximate results. To be used for example when the image has been prepared in a drawing application, by drawing a closed line representing section's geometry, then filling it.
3)With the third sheet the row of pixels at the periphery is completely removed. This will generally give conservative results.
An important feature of the procedure used here is that, by choosing one of three sheets, you can specify how to handle the single row of pixels that's all around the periphery of the image.
1)With the first sheet all pixels in the image are kept entirely: this is a normal procedure, but in many cases can give unsafe results. To be used if you know that the pixel map exactly represents the geometry of your section.
2)With the second sheet the row of pixels at the periphery is considered effective only at 50%. This will often give best approximate results. To be used for example when the image has been prepared in a drawing application, by drawing a closed line representing section's geometry, then filling it.
3)With the third sheet the row of pixels at the periphery is completely removed. This will generally give conservative results.
User defined section: instructions
Closely follow the following steps to obtain the best results from this application.
Below you find a more detailed description, that you'll need to know only rarely under special circumstances.
1) The file defining the section to be analyzed must be prepared by means of a suitable drafting software: as an example, AutoCadŽ allows for creating a .BMP file from any drawing.
2) The graphics file, if it is not already a .BMP or a .PNG, must be transformed in one of the two formats accepted by this application: most graphics editors allow for this transformation
3) In creating the image file use afap 2 colors only: white for the background and black or any dark color for the foreground
4) At this point get into www.xcalcs.com, login, open the sheet you copied from 'My section', click the blue image to the right of the figure, and, in the forthcoming dialog, input the name of the file prepared as above. Click OK to upload the image and submit it (and please be patient if the image is large)
5) If there were no problems, the sheet is reloaded and you'll see your image in blue appearing to the right of the figure: you'll need only to define the height of the section to get what you were looking for.
1) The file defining the section to be analyzed must be prepared by means of a suitable drafting software: as an example, AutoCadŽ allows for creating a .BMP file from any drawing.
2) The graphics file, if it is not already a .BMP or a .PNG, must be transformed in one of the two formats accepted by this application: most graphics editors allow for this transformation
3) In creating the image file use afap 2 colors only: white for the background and black or any dark color for the foreground
4) At this point get into www.xcalcs.com, login, open the sheet you copied from 'My section', click the blue image to the right of the figure, and, in the forthcoming dialog, input the name of the file prepared as above. Click OK to upload the image and submit it (and please be patient if the image is large)
5) If there were no problems, the sheet is reloaded and you'll see your image in blue appearing to the right of the figure: you'll need only to define the height of the section to get what you were looking for.
User defined section: more information
This calculation sheet is for determining inertial properties of a section defined by a pixel map. More information
upon calculation methods may be obtained upon request: in this event please always specify the reason for the request (perhaps an
unexpected result). The precision of results will of course depend also on image resolution: a typical image 256x256 pixels will
be sufficient for most applications.
The image file to be analyzed must be structured in order to allow for recognizing, among all colors included, the colors representing the background and those representing the foreground (the actual section); this application works as follows: it considers as the foregroung any color with a brightness (R+G+B) smaller than 50%, and the other colors are the background.
If you get a fully white or a fully blue image, or another unexpected result, there was likely a problem in the color recognition: get a 2 color image to avoid any misinterpretation.
Please note also:
- the image cannot be interlaced.
- any white padding around the solid section is removed during file analysis
- if your editor allows for defining the physical image size (or pixel density) and if such information goes into the image file, it shall be used. Otherwise you shall be able to define the section dimensions in the calculation sheet. The aspect ratio (ratio of horizontal to vertical pixel density) will always be 1, even if your file specifies something different: you should account for that in building you image.
The image file to be analyzed must be structured in order to allow for recognizing, among all colors included, the colors representing the background and those representing the foreground (the actual section); this application works as follows: it considers as the foregroung any color with a brightness (R+G+B) smaller than 50%, and the other colors are the background.
If you get a fully white or a fully blue image, or another unexpected result, there was likely a problem in the color recognition: get a 2 color image to avoid any misinterpretation.
Please note also:
- the image cannot be interlaced.
- any white padding around the solid section is removed during file analysis
- if your editor allows for defining the physical image size (or pixel density) and if such information goes into the image file, it shall be used. Otherwise you shall be able to define the section dimensions in the calculation sheet. The aspect ratio (ratio of horizontal to vertical pixel density) will always be 1, even if your file specifies something different: you should account for that in building you image.