Resolution-aware Slicing of CAD Data for 3D Isidore Onyeako and Won-sook Lee School of Electrical Engineering and Computer Science, University of Ottawa, Ontario, Canada Keywords: Additive Manufacturing (AM), Layered Manufacturing (LM), 3D Printing, Computer Aided Design, Fused Filament Fabrication (FFF), Fused Deposition Modelling (FDM), Electron Beam Freeform Fabrication (EBFF), Electron Beam Melting (EBM), Magnetic Resonance Imaging (MRI), Computer Tomography (CT), Rapid Prototyping (RP), Stereolithography (SLA). Abstract: Low resolution printing results in fused joints when the joint clearance is intended to be very small. Various 3D printers are capable of print resolutions of up to 600dpi (dots per inch) as quoted in their datasheets. It is imperative to include the ability of a 3D slicing application, to validate 3D models, based on the ability of the printer to properly produce the features with the smallest detail in a model. A way to perform this validation would be the physical measurement of printed parts and comparison to expected results. Our method uses ray casting to detect features in the 3D models whose sizes are below the minimum allowed by the printer resolution. Our model was tested using few simple and complex 3D models. Areas in the slices with thickness less than the specified resolution were detected. Our model serves two purposes: (a) to assist CAD model designers in developing models whose printability is assured- by warning or preventing shape operations that will lead to regions/features with sizes lower than that of the printer resolution; (b) to validate slicing outputs to identify regions/features with sizes lower than the printer resolution. This makes our model very powerful in the quality assurance of 3D printing and a huge cost/time saver when planning for 3D printing. 1 INTRODUCTION When 3D printing equipment manufacturers quote their printer resolutions, this information can serve as an input into a model to validate that the applicable printer will be able to produce critical features in the model of interest. The potential cost and time savings, gained by ensuring that CAD designers avoid features smaller than the printer resolutions, is quite significant. 1.1 Basic 3D Printing Process 3D printing (3DP) or rapid prototyping (RP) is an additive manufacturing process that involves the production of physical objects by adding thin successive layers of materials without using moulds (Munir, 2013). The models being printed can be obtained via image acquisition from mobile scanners (Stamos, I., Allen, P., 2000), Magnetic Resonance Imaging (MRI), Computed Tomography (CT), positron emission tomography, direct 3D CAD models. This enhances the rapid prototyping process as the technology is capable of producing a near-net- shaped and multi-coloured part. 3D printing is also referred to as Layered Manufacturing (LM) (Munir, 2013) The 3D printing process (Figure 1) starts with a CAD data model generation. The data is “sliced” into successive layers. A slice is a collection of contours to be filled during printing. Create CAD Slice CAD Print model Figure 1: 3D Basic Printing Workflow (Topcu, O., Tascioglu, Y., Unver, H. O. 2011). 1.2 Slicing and 3D Printing Quality Assurance The process planning of additive manufacturing, as shown in Figure 1, begins with the creation of the CAD model. This can be done with any of the popular 3D applications. It can also be obtained from 3D medical imaging data. 124 Onyeako, I. and Lee, W-s. Resolution-aware Slicing of CAD Data for 3D. DOI: 10.5220/0005784701220127 In Proceedings of the 11th Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP 2016) - Volume 1: GRAPP, pages 124-129 ISBN: 978-989-758-175-5 Copyright c  2016 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved