Preliminary Instructions for Measuring Boat Decks
Do you want to improve your complex measuring and templating task for boat deck replacement? PhotoModeler can help with that.
We are currently developing tutorial videos and procedure manuals for this process. We hope to release these before the end of 2019. In the interim, if you want to get going now (and you don’t mind a less defined process and some experimentation), this page provides a preliminary guide.
The concept for replacing physical templating with digital templating for boat deck measurement is to use your camera to take photos of the deck that has special targets placed on it. These targets are temporary and will not damage the boat. These photos are loaded into PhotoModeler which determines where the targets and hence the deck surfaces are in 3D space.
In PhotoModeler you then use a tracing method to outline regions of the deck (such as the edge of non-slip areas). The output is a 2D drawing with all the accurate deck areas in a cohesive CAD file.
The CAD file is exported from PhotoModeler and imported into your CAD or CAM software for additional cleanup, and tool path planning for each deck section. The deck material is cut and installed.
First, we assume, that you are familiar with measuring boat decks using traditional templating methods, and are already using CAD and CNC cutting.
The steps you will follow is very similar to that described in the sink video. This is a good place to start and a good overview. Imagine the sink outline (cutout in the countertop) was a deck non-slip area to be modeled.
Download the PhotoModeler Standard evaluation version. Decide on your camera (it can be a mobile phone for the first experiments).
We strongly recommend that you experiment and test in the comfort of your office or factory first. Do not do your first project on a real boat. Perhaps use some masking tape to outline some pretend deck areas on the floor, place the targets (tape them to the floor), take your photos, and process in PhotoModeler. Use a scale and compare your measurements and CAD data to the real world. You might even go as far as cutting out some paper or cardboard with your CNC cutter and placing it back on the taped floor to see that it fits.
At any time please send your project data to PhotoModeler Support (use the ‘Send Files to Support’ tool in PhotoModeler) for any help and guidance.
How to place targets
You will use the PhotoModeler program to print sheets of Coded Targets. See the ‘Printing Coded Targets’ video below. You can use whole sheets of targets, or you can cut them into smaller sets. If you cut, keep the ID number with the target for later QA.
With the targets on the deck, you are defining surfaces. You can place a target sheet in the middle of each deck area for example. One key is that every photo should have 8 or more targets appear in it and with good spread (not a small area and not in a line). Then when photos overlap, there need to be at least 6 to 8 targets shared between each overlapping photo pair. Another key is you don’t just need to put targets on the surfaces you want – they can be spread throughout the scene to help the program, not just in measurement areas of interest. It is important that the targets cover the areas, cover the photos, and aren’t in a straight line. Think ‘spread out’.
The boat can be on the water, dry-dock, or in a factory. The only thing to watch for if the boat is in the water is excessive flex of the boat. This would only be a concern if the boat was not rigid, you are modeling a large area at once, and there is a big motion of the boat in the water.
See the sink video below for an example of placing target sheets. The targets should not move, so if using paper tape them to the deck (without obscuring the targets). When starting, err on more targets and more photos than you think you need. With experience, you may find you can reduce this.
After the targets are placed you will want some accurate scale measurements. Use a tape measure and accurately measure between pairs of targets on the deck (longer distances if possible). Write down the two target IDs and the measurement for each pair. Use pairs at different angles and in different locations on the boat.
How to take photos
Each project will be different but starting with the simple case first. Imagine a very flat deck or a swim platform with few obstructions. After the targets are placed, you will take multiple photos from different positions. The camera will point down towards the deck and you will step along ensuring the photographs overlap.
Error on the side of too many photos to start. With a digital camera, they are basically free.
In more complex situations you may need to take more photographs from different angles.
The steps in PhotoModeler
This is a rough outline of the steps you would take in PhotoModeler to process your deck project. A lot of detail is missing here. You can learn these steps by following the videos below, and by viewing additional PhotoModeler Tutorial videos. Some of these steps can be automated and automation improves with the 2020 release (contact Support for more).
- Start PhotoModeler Standard.
- Start an Automated Targets project.
- Load the photographs of deck and targets.
- Load a pre-calibrated camera or ask for automatic calibration.
- Process, and then check the results (look at the 3D Viewer, look at high residual points).
- Define your scale and coordinate system based on solved 3D points. The coordinate system is the xyz system and provides the correct top-down view on export.
- Define Plane Surfaces (usually Fit Plane To Points) for each deck section (or if the boat is overall quite flat it is better to fit all the deck points to one plane surface.
- Using Surface Draw, outline the deck regions (such as edges of non-slip) by drawing on the surfaces in the photos. For each region, it is usually best to pick the photo(s) where the area of interest is under the camera center and the camera is pointing straight down. See the image below.
- When all regions are outlined, use the File Export to export into your favorite CAD format. Normally you will want to do a 2D export but there are some caveats for curved decks (contact PhotoModeler support).
A summary of videos that can assist in learning.
- Coded Target tutorial. Shows the basic steps of using Coded Targets in PhotoModeler.
- The sink video. Shows using targets, surfaces, and surface draw which is a process very similar to outlining deck regions. The associated article.
- Example target layout. Shows a raw video of placing targets (sheets attached to backing) on a deck.
- Printing coded targets. Shows a tip video on how to create targets in the PhotoModeler software.
- Scale / Rotate / Translate tutorial. Shows how to scale projects and set up correct rotations for CAD export.
- Camera Calibration tutorial. Shows how to calibrate your camera when you are ready for higher accuracy.
If you want to be kept informed of when the decking procedure manuals and videos are published please email us.