Understanding Rasterization Settings and Output Files


#1

I’m interested to know more about the contents of the text file output along with the two folders containing 1bit bitmaps during Rasterization.

Example output text file:
[Build]
Format version = 1;
Layer thickness = 0.03;
Number of slices = 600;
[Materials]
Material1 = C:\directory\torus\a_torus\a_xxxx.bmp
Material2 = C:\directory\torus\b_torus\b_xxxx.bmp

How does the “Rasterization Resolution” settings impact the output bitmaps?
When I set these to X: 300, y: 300, and Z: 300 I get 600 bitmaps at 608px x 600px out. I’m not sure I understand how these values are related?

What are the physical units of “layer thickness” as shown in the output text file?

What are the physical units overall of the images output? ie. What can be expected to translate to the printing process.

Note: I’m trying to understand all this because I have access to polyjet technology and voxel level resolution printing.


#2

Hi rjduran. Thanks for your input. We’ve completely overhauled the rasterization process and exporting raster and vector maps is now much more straightforward. In the next release, you will have much more control over all of the export options. We hope to make a new release soon. Please stay tuned.


#3

Thanks for the info @andrew.payne. I’m experimenting with the output options in the latest release (8/17/16). The export options are much more intuitive now. Since the user manual hasn’t yet been updated to reflect the changes, I now have more questions about printer resolution and UI suggestions for the right hand side info pane and preview pane in voxel slicing mode.

  1. Question: In your experience, how does one understand the Printer Resolution parameters? Are these values the same for most stratasys printers (I have access to an objet260 connex3)?
    X: 600
    Y: 600
    Z: 847.457627118644

  2. Question: Do the bounding box dimensions now match the physical printed dimensions? The new vertical slice level bar seems to indicate this.

  3. Question: I don’t see the option to export support material bitmaps. Is this possible yet? (Original question in other post: Generating Support Material Bitmaps)

  4. Suggestion: Add a zoom feature to the raster/vector preview pane so you can see the whole raster layer. Its nice to be able to zoom and pan around to parts of it like in other 2D/3D CAD tools.

  5. Suggestion: Make the text fields that can be changed (ie. Printer Resolution values) a different color than white. Its difficult to read white on a gray background.

Thank you!


#4

HI rjduran. Thanks for your question. I’ll try to respond to each in turn. Please see below.

Question: In your experience, how does one understand the Printer Resolution parameters? Are these values the same for most stratasys printers (I have access to an objet260 connex3)?
2. X: 600
3. Y: 600
4. Z: 847.457627118644

The printer resolution, in this case, is the DPI (dots-per-inch) of the images used to lay down each layer (typically using a polyjet printer like a Stratasys Objet printer). Polyjet printers (mostly) convert your 3D model into slices. Each slice contains a black and white image where a white pixel represents a single drop of resin and a black pixel represents no resin. For multimaterial printers, each nozzle receives a different set of images. So, the numbers that are shown in the dialog box above represent the image size (in X&Y) for the raster slices that are generated. If you change the DPI-X or DPI-Y values, you’ll notice the raster preview in the preview window below will change too. The DPI-Z is basically the number of slices per inch. Each printer has a Z-resolution which represents how ‘fine’ the layer slices will be when laid down. Since you mentioned the Objet 260 printer, you can find specifications on their website (http://www.stratasys.com/3d-printers/design-series/objet260-connex3). According to their literature, their build resolution is X-axis: 600 dpi; Y-axis: 600 dpi; Z-axis: 1600 dpi… although you probably want to confirm the exact dimensions in the literature for your specific printer.

Question: Do the bounding box dimensions now match the physical printed dimensions? The new vertical slice level bar seems to indicate this.

Yes, the bounding box now is specified in units (which is currently displayed on the left hand side of the dialog box in the picture you posted. You can change the size/resolution of the voxel boundary volume by clicking on the “Resize” button under the Main panel on the left side. However, if you simply want to change the units your using (from inches to mm, for example) then you will want to click on the three-bar icon just to the right of the Main panel. This is the Options/Preferences dialog box and contains several menu items, one of which is called Units. If you select that, you’ll see the current units of your model. You can change the units in the drop down and depending on whether or not the Rescale Model check box is checked, then it will scale up/down your model. When you change your model units, the units should be applied globally. So, when you turn on the vertical slice clipping plane, you’ll notice the Z-level slider shows the correct units. Similarly, in the model info dialog (that you took a screenshot of), the units for the slice size will be changed too.

I also want to highlight another menu item that could be helpful. In the same drop-down menu used to change the model units, you’ll find another item for Printers. If you select this menu item, you’ll see an interface that allows you to specify some printer attributes. There is a drop-down list of some available printer types. If you click the check box to show the build volume in the viewport, then you’ll see blue lines in the 3D viewport that show you the boundary of the printer bed. There is also an alignment widget which allows you to align your voxel boundary volume to the printer boundary volume. These may come in handy when exporting geometry/slices, etc.

Question: I don’t see the option to export support material bitmaps. Is this possible yet? (Original question in other post: Generating Support Material Bitmaps)

If you have selected the Voxel Slicing top-level workflow icon (top right near the close window button), then you’ll see the entire dialog which allows you to determine how to ‘slice’ up your voxel model. Just below the model information dialog, you’ll see a drop-down menu that says “Slice Type”. Raster slicing will create pixel-based images where each image you see is a slice through the model. The drop-down menu just below the “Slice Type” allows you to determine how to create those images. If you change the slice type from Raster slicing to Vector slicing, then you will get a different set of options. Vector slicing creates vector geometry (polygons) based on the voxel geometry. Eventually, the vector geometry can be used to generate g-code to send to different types of FDM style printers… but we haven’t exposed the g-code generation just yet. But, the vector slicing will create a vector preview of each slice. Both Raster and Vector slicing generally have image preview options which allow you to fine tune how the image is created. In vector slicing preview options, you can turn on/off the start point for each polygon, show the curve direction, and adjust the resolution of the curves that are generated. Raster previews also have options, but only if you’re not using the Printer Resolution with Pattern generator. This particular slicing generator creates a full-scale image of the slice, using the DPI-X and DPI-Y that is specified in the Printer Resolution dialog box above. If you change the DPI values, you’ll see the image preview adjusts.
Now, back to your original question about exporting… At the bottom of the slice preview window, you’ll see a bar that says “Export Options”. If you click on that, it will expand upwards to display a series of controls. These options change based on the slice type you’re using (raster vs vector). Raster exporting allows you to export stacks of images (ie. jpg, png, bmp, tif, etc). You can either choose to export the current preview (so whatever slice is currently being shown) or you can select one of the other items in the drop-down menu. Currently, there are two other presets which will automatically export the proper files for sending slices to an Objet or an Ember printer. Now, if you have vector slicing selected, it will give you a different set of options. With vector slicing selected, you can export a stack of slices in different formats. Currently, SVG, CLI, and Rhino files are supported… but we’ll likely add more soon.

Suggestion: Add a zoom feature to the raster/vector preview pane so you can see the whole raster layer. Its nice to be able to zoom and pan around to parts of it like in other 2D/3D CAD tools.

Thanks for the feature request. In fact, it’s already implemented (at least partially). As previously mentioned, the raster preview creates images that are determined on the DPI printer settings. In this case, a single pixel on your screen represents a single drop of resin. It’s displayed at 100%. We didn’t want to introduce zooming here because we would need to create interpolations between pixels at various zoom levels and we thought it was more accurate if we kept it at 100%… Obviously, this is open though and feedback is welcome. If the image is larger than the display width, then you’ll get scroll bars to pan around the image. Now, vector slicing is a little bit different. If you choose this slice type, then you can zoom (middle button) and pan (left button). So, with vector slicing turned on… you do have the ability zoom/pan as requested.

Suggestion: Make the text fields that can be changed (ie. Printer Resolution values) a different color than white. Its difficult to read white on a gray background.

Thanks again for your suggestion. Obviously, this is a stylistic preference… but we didn’t want to force you to use whatever preferences we specified. Rather, you can pretty much change every aspect of the UI color scheme. If you click on the three-bar menu item (next to the Main panel) you should see one of the menu items says UI customization. Here you can select any UI control (ie. the one you would want to change is called “editable text”) and modify the attributes.

I hope this helps clarify some of your questions. Feel free to respond if you have any others!


#5

Thank you @andrew.payne. All of this really helps.

The only clarification I have is on Question 3. I understand that the bitmaps exported are for two single materials deposited with a certain material ratio. But what about bitmaps for the deposition of support material? I’m still new to the process but I thought all materials used require bitmaps?

Separate from the previous question, I have a followup question regarding materials and their representation in the tool. Currently, the tool only operates on two possible materials and visualizes this with arbitrary colors. I understand this as something like Material 1 = Vero and Material 2 = Tango, etc in Stratasys systems. I’m curious about what it might take to generate bitmaps that can work with color combinations as is found in combining varying amounts of Vero Cyan, Magenta, and Yellow material at print time.

Thinking through this leads me to ask if there is a way to generate 3 sets of bitmaps corresponding to the three colors (typically loaded into the system as separate cartridges)?

I assume I could try just duplicating one of the material bitmaps 2x so I ended up with 3x “material 1” folders (ie. a1_, a2_, and a3_). Due to the nature of 1 bit bitmaps and the printing process, it seems that if you had 3 bitmaps corresponding to the 3 vero colors it would be an issue to be mixing each color at a full 100% (1 bit = white pixel = 100% material placement). The swatch below is what I’m talking about with mixing colors.