using a mobile phone as a 2d virtual tracing tool: static peephole vs. magic lens
TRANSCRIPT
Using a Mobile Phone as a 2D Virtual Tracing Tool: Static Peephole
vs. Magic Lens
Klen Čopič Pucihar, Matjaž Kljun, Paul Coulton
There are many people who like to create and make things with their hands. These people to create all sorts of paintings.
Or sawing their own clothes.
Or build models from balsa wood such as houses
Or Planes.
In the process of making these things they are regularly faced with the taskk of transcribe inforrmation from one object to another.
For example when building minature plane model. Creator needs to transcribe designs from blueprint to balsa wood prior to cutting (transcription is done from blueprint to balsa wood).
Or, when they saw their own cloths, they need to cut the material prior to sawing, hence the cutting plan needs to be transcribed to the fabric (transcription is done from sawing pattern to fabric).
Or you are not very skilled at setting the correct perspective or porpotions so you use existing designs to help you set out drawing plan (transciption is done from printed template to semi transparent surface such as tracepaper.
All this tasks requre the creator to transcribe infromation from one object to another. So lets look now at how people actually do these things.
There are many ways in which one can transcribe information from one object to another. For example skilled artists can achieve this transcription by mapping their observations to this new layer. This is ok for artistic elements, but not very effective for istuations where correct size of the object is esential for sucesful end result.
An alternative options is to use template technique. Which can work by placing a template bellow a semi transparent paper (trace paper). Or by putting and indigo paper bellow template. At the place of exerted pressure, indigo will leave a mark on the underlaying surface.
Traditional Sketching Aids
Alternative to templates are stenciles which are cut out templates that let users follow the edges in order to transcribe the information.
In both cases one needs to production such templates or stencils which is time consuming, difficult and limiting specially in case of bigger formats. For example how many of you have access A0 printer or printer bigger than A3?
One possible solution is virtual tracing using virtual templates.
Virtual tracing is a method of transcribing instructions from virtual template shown on mobile device screen onto underlaying surface (paper) . The mobile device renders a virtual template image, such as a contour line, onto device screen together with a live video stream of the drawing surface.
One possible solution is virtual tracing using virtual templates.
Virtual tracing is a method of transcribing instructions from virtual template shown on mobile device screen onto underlaying surface (paper) . The mobile device renders a virtual template image, such as a contour line, onto device screen together with a live video stream of the drawing surface.
Video
This paper evaluates a mobile phone as a virtual tracing tool and compares it with traditional sketching aids. We compare 3 interfaces:
a traditional tracing method with a printed template, a virtual tracing method Static Peephole (SP) a virtual tracing augmented reality Magic Lens (ML)
Compared to traditional methods, virtual tracing has a clear advantage in that it does not require the physical production of sketching aids, which is particularly problematic when one desires to draw on large formats.
In case of virtual tracing, the drawing size is not limited; although, when the drawing surface does not fit on the screen, one needs to move the device in order to reveal the unfinished drawing surface.
The core challenge is alignment of the virtual template with what has been drawn thus far! - In SP interaction the user uses touchscreen gestures to align virtual contour with wath has been drawn this far. - In ML mode the the alignment is done automatically as long as it is possible to track the camera pose in relation to the drawing surface. As the alignment is done at each rendered frame, the user does not need to keep the device perfectly still while drawing a particular segment and may hold the phone in hand. (As you saw in demo video.)
However, the ML is highly dependent on camera tracking which may diminish sketching experience, particularly as it is difficult to implement robust and accurate camera tracking on a blank drawing surface where the hand holding the pencil can occlude segments of the scene.
Additionally, when compared to traditional sketching aids, both virtual tracing methods require the user to look through the phone while sketching and only show a segment of the image being drawn at the time.
Template Static Peephole Magic Lens
Research questions• How effective are phones in supporting user
sketching through virtual tracing?• Do users find the advantage of the ML useful?• Can users’ draw whilst holding the ML in hand?
To answer these question we run a user study where users were asked to sketch a cartoon character using the aformentioned three different method. Template, SP, ML.
We had 7 participatnts aged between 23 and 45 (3—employed, 4— students) coming from verious backgrounds (1), architecture (1), computer science (3), medicine (1) and mechanical engineering (1).
Participants were asked to complete the task as quickly and as accurately as possible. Each participant complete three drawings, one with each method.
Task
Data Collection• Drawings• Task time• QUIS (overall reactions)• Open ended questions:• Rank interaction modes and justify their decision• Highlight the most difficult part of the task
We took 3 drawings each participants finished and ranked them from best to worst. This was done by two researchers independently.
Looking at quality ranking results on the right we can see that the differences are not very big, however the Template method ranked best followed by ML and SP method.
Quality
Conclusion: •It is possible to use mobile phones for virtual tracing.•Virtual tracing whilst holding phone in hand is possible.
Looking at time it is obvious that traditional sketching method is the fastest, whilst there is only small advantage of ML over SP.
This is surprising as in SPparticipants had to manually align the sketch every time they moved the phone.
Time
Conclusion: •Users are very good at manually aligning the virtual contour with what has been drawn this far. •Automatic alignment using a marker is not good enough.
The same trend is shown by QUIS scores. Template is marked as best, whilst there is only small difference between ML and SP. Supporting our previous conlcusions.
QUIS
RankLooking at ranking results the same trend emerges.
So now we are left with observational results.
Observational results• Participants adjusted the stand or held the phone at a distance of 17-22
cm. • When drawing, participants always looked at the paper through the
phone keeping the pencil within the cameras’ field-of-view. • Participants looked at the paper to see how they were progressing. • In SP, participants drew all instructions within the screen segment,
including those at the very edge of the screen. • In SP mode participants expressed the need for a minimap.
Conclusion• It is possible to use mobile phones for virtual tracing,
although, traditional methods continue to be quicker.• Virtual tracing whilst holding phone in hand is possible. • ML only achieved comparable performance to SP
mode. This coupled with users’ dislike of the marker suggest that currently available tracking solutions are not good enough.
Future work• Look into ways of detecting what has been drawn thus
far.• Run a study with more participants to get conclusive
results. • Explore the use of a stand in the context of the ML
interaction mode.• Evaluate virtual tracing using virtual mirror metaphor.• Look into ways of supporting transcribing 3D
information to objects (sculpturing aids).
