CAD course creative projects necessitate subjective feedback. In academia, peer review is a widely used instrument to gather diverse and timely feedback which stimulates learning and engagement in students who review one another. To date, however, no effort to summarize and score subjective content from peer review text via sentiment analysis has been attempted in an educational setting, including CAD courses many of which naturally employ a project-based architecture. This is perhaps due in part to a lack of specifically tuned tools. Towards meeting this need, we introduce a new lexicon compiled from actual peer review text, implemented specifically in a CAD-course context, and compare it to other publicly available lexicons. HeLPS, our domain-dependent lexicon, performed more concisely and accurately in our CAD courses and consistently tagged high-quality positive and negative sentiment with a lexicon a fraction of the size of others. Both qualitative and quantitative evidence suggest that HeLPS is the preferred option for identifying subjective opinion towards CAD course projects.
A Domain-Dependent Lexicon to Augment CAD Peer Review
Z. Beasley and L. Piegl
Computer-Aided Design and Applications, Vol 18, No 1, pp. 186-198, 2021
Assessing the quality of 3D printed models before they are printed remains a challenging problem, particularly when considering point cloud-based models. This paper introduces an approach to quality assessment, which uses techniques from the field of Topological Data Analysis (TDA) to compute a topological abstraction of the eventual printed model. Two main tools of TDA, Mapper and persistent homology, are used to analyze both the printed space and empty space created by the model. This abstraction enables investigating certain qualities of the model, with respect to print quality, and identifies potential anomalies that may appear in the final product.
Inferring Quality in Point Cloud-based 3D Printed Objects using Topological Data Analysis
P Rosen, M Hajij, J Tu, T Arafin, L Piegl
Computer-Aided Design and Applications 2019
This paper introduces and extension to our previous papers to handle anomalies in the point based object slicing method. The anomalies handled are point, line and plane touch cases as well as overlaps. These anomalies can cause major problems in any intersection procedure, yet, they are seldom discussed, let alone handled. It turns out that the point based approach is capable of handling these special cases with minor extensions.
Handling Anomalies in Object Slicing for 3-D Printing
W Oropallo, L Piegl, P Rosen, K Rajab
Computer-Aided Design and Applications, 2019
The advancement of technology and its application to the field of education has caused many to re-examine the merits and pitfalls of cyberlearning environments. Though there is a wealth of research both for and against its mainstream use, there is a consensus that much work remains to be done in key areas such as collaboration, course content, personal learning environments, and engagement. CAD and cyberlearning share a common goal: to communicate information effectively. Unfortunately, many aspects well understood in CAD have been overlooked in online education. In this paper, ten key challenges and their implications for CAD cyber education are discussed. The purpose of this paper is not to provide a dismal outlook for cyberlearning, but to incite discussion, research, and development into these areas with the anticipation of a viable and attractive alternative to traditional classroom education.
Ten challenges in CAD cyber education
ZJ Beasley, LA Piegl, P Rosen
Computer-Aided Design and Applications 15 (3), 432-442
This paper revisits a more than half a century old problem: slice a free-form object into layers for manufacturing. A point based approach is taken that would have been prohibitive even a decade ago. Due to modern hardware, plenty of storage and a plethora of software packages, the time has come to ditch complicated and error prone numerical code and deploy a simple point based method to achieve robustness and accuracy that have been lacking for a very long time.
Point cloud slicing for 3-D printing
W Oropallo, LA Piegl, P Rosen, K Rajab
Computer-Aided Design and Applications 15 (1), 90-97
3-D printing, also known as additive manufacturing, has gained a lot of attention both within and outside CAD research. Even popular media have touted the technology as one of the game changer technologies of the 21st century. Simply stated, most printing devices add material to an unfinished part, layer by layer, until the entire object is completed. In order to make this happen, the object is sliced into thin layers which are produced and glued together. Since NURBS are the standard form of modeling tools, the process entails converting the NURBS into an STL model (piecewise triangular model) which is then sliced into a set of closed polygonal loops. In order to avoid the many problems with the STL-based slicing, in this paper we investigate a point cloud-based approach to direct slicing of NURBS based models. It uses the original NURBS model and converts the model into a point cloud, based on layer thickness and accuracy requirements, for direct slicing. The only major computational requirement is point evaluation which can be done error free and in an inexpensive manner. The generation of the point cloud is the main topic of this paper.
Generating point clouds for slicing free-form objects for 3-D printing
W Oropallo, LA Piegl, P Rosen, K Rajab
Computer-Aided Design and Applications 14 (2), 242-249
Three dimensional printing has gained considerable interest lately due to the proliferation of inexpensive devices as well as open source software that drive those devices. Public interest is often followed by media coverage that tends to sensationalize technology. Based on popular articles, the public may create the impression that 3D printing is the Holy Grail; we are going to print everything as one piece, traditional manufacturing is at the brink of collapse, and exotic applications, such as cloning a human body by 3D bio-printing, are just around the corner. The purpose of this paper is to paint a more realistic picture by identifying ten challenges that clearly illustrate the limitations of this technology, which makes it just as vulnerable as anything else that had been touted before as the next game changer.
Ten challenges in 3D printing
W Oropallo, LA Piegl
Engineering with Computers 32 (1), 135-148