Location
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St Helena Island, SC 29920
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History
A chapel of ease is a church building separate from the main parish, but still located within those boundaries, where it is closer in proximity to those who could not attend the main parish church. This was commonly practiced in Great Britain with the intent to provide the "ease and comfort of parishioners living some distance from the main parish church."
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The Anglican Church in colonial South Carolina established both Chapels of Ease in St Luke’s and St. Helena’s Parishes, both in Beaufort County. In total, there were four chapels of ease within Beaufort County during the 18th and 19th centuries. St. Helena’s Chapel of Ease was built in the 1740s for the planters who lived on St. Helena's Island which is approximately eight miles away from Beaufort.
The chapel itself is constructed out of tabby with brick outlining the window and door openings. Tabby is a type of concrete made by burning oyster shells, which creates lime. This is then mixed with sand, ash, broken oyster shells, and water to create a highly durable building material. This mixture was used by early Spanish settlers from the North Carolina to Florida regions of America. English colonists then used tabby to build in the coastal communities of Georgia and South Carolina. Tabby is usually protected with a coat of stucco, which could be seen on the Chapel of Ease during our field studies.
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The chapel is a little over 56 feet long and 30 feet wide with four thick walls and is now considered ruinous since there is no roof, flooring, or windows. Unfortunately, on February 22nd, 1886, the chapel was damaged by a forest fire. There was also a significantly large mausoleum located on the opposite end of the property that many of us wanted to document as well.
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Site Visit
We visited the location on October 2nd 2015. Unfortunately, only half of the class could attend because of previous commitments. We unable to scan earlier due to heavy rain in the area, which would absolutely destroy the laser scanner. Throughout the entire process of scanning, I took pictures in order to reference them during the registration process as well as to document the overall project.
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Above is a hand drawn site map of the area in which we laser scanned. The arrows show the limits we set the Farro Laser Scanner to and the direction in which we scanned. This is very important to have when aligning the laser scans up and deleting those that are unnecessary. Below is a set of field notes taken on the day that we visited. Field notes are specifically helpful when a scan has been improperly started and needs to be deleted in the lab.
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For example, scans 7 and 9 somehow didn't scan properly in the and needed to be deleted in the lab. Without these field notes, it could be confusing to understand the order in which we scanned, especially since only half of our class was able to go. The list also lets us know which scans were preview scans, and could be deleted when uploading them into the computer. Preview scans are necessary to understand the area in which we are scanning, but are not necessary during the uploading and registering process. This whole process took about two and a half hours to complete. Compared to a project completed in a previous quarter, laser scanning takes a significant amount of less time than hand measuring and documenting on a computer.
Registration
The next step is to go back to the computer lab and register the scans onto the computer using several programs. The Farro Laser scanner automatically creates "scene" files. We first had to open up these files and delete the preview scans as well as make sure that scans 7 and 9 were deleted completely.
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The following instructions were provided by Professor Keller during this whole process:
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Copy and paste the CoE folder found here T:\HIPR-312-01\_MATERIAL\Chapel_of_Ease to your local hard drive
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Open Faro Scene
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File > open > CoE.lsproj (this file is located in the CoE folder)
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Using the field notes delete the preview scans from the workspace
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Next select the scan > right click > load
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With scan selected in the workspace window > right click > view > planar view
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With scan selected in the workspace window > right click > operations > color pictures > apply pictures
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Repeat steps 5-7 for all scans
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File > save
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Click on the Gexcel dropdown
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Make sure all scans are selected, the number 1 is in the box
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Color and reflectance export options are checked
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Save in folder
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Open the Reconstructor project file
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Repeat steps from previous project
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Process scans
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Clean up data by removing unwanted points
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Manual registration
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Registration
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Batch Registration
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Instructions like these were very helpful in understanding how to properly complete this process. Below is an example of what the scans look like without the colored images applied. Without going through this process, the images would lack color.
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Scan 1: Preview
Scan 2: Full, with mausoleum
Scan 3: Full, 360 view
Scan 4: Preview
Scan 5: Full
Scan 6: Preview
Scan 7: Full DELETED
Scan 8: Full
Scan 9: Preview DELETED
Scan 10: Preview
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Scan 11: Full
Scan 12: Preview
Scan 13: Full
Scan 14: Preview
Scan 15: Full
Scan 16: Full, 360 view
Scan 17: Preview
Scan 18: Full
Scan 19: Preview
Scan 20: Full
Once you complete the above steps, you can now open up the file in JRC Reconstructor. All of your scans are now located under the title bar “grid point clouds.” The first step is to process all of your scans, you do so by making sure that the scan is selected by left clicking it. Then click “process.” Select “start” on the next window and when it’s done, simply press “close.” Repeat for each scan. Once that is done, you can re-load all of your point clouds, which will look similar to the image below. They are not yet lined up because you still need to register them.
The next step is to clean up all of the scans individually. This is done by using the selection tool to delete the “noise” surrounding the building and any unnecessary landscape surrounding it. Be careful when doing this because JRC has no delete button. If you mess up on one point cloud, you will have to reload it in order to fix the mistake.
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After cleaning up the scans, you need to go through the preregistration process. You do this by clicking on “Go to Line Up” and “Manual Preregistration.” By using scans 1 and 2 as examples, you can follow the steps below:
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Select scans 1 and 2.
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With both highlighted, select the Preregistration icon.
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Set scan 1 as the Reference Grid and 2 as the moving grid.
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Notice the scans appear in the either window.
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Hold the ctrl key on the keyboard and move your mouse over the scan. Notice this is reflected in the smaller windows at the top of the screen. These windows can be positioned and enlarged.
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When preregistering scans we need to find 3 corresponding points on both scans. Select the point on the right side of the screen first and then the identical point on the left. Attempt to space them out around the scan
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After 3 points are selected, click the Compute Any error below .5 meters is good.
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Select Apply Transform and then
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Notice the models have shifted and are now preregistered.
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If this is not correctly, your scans have the potential to not line up or even flipped upside down in some cases. This whole idea of stitching these scans together is helped by preplanning the order of scans that you register.
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After preregistering, the next step involves registering the scans. Follow the steps below:
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Make sure scans 1 and 2 are still selected and select the Registration
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In the registration window, select scan 1 and then select the Set as reference
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Select the Process Wait a few minutes for the scan to register. Anything under .5 is fine. Select Apply transform and then Close. The two scans are now registered.
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Repeat the steps for the remaining scans.
After registering the scans, you need to create a bundle adjustment by designating only one scan as moving, and the rest as reference. You then need to repeat the same process, changing the moving scan every time.
After completing those steps, you can now combine all of the scans into one point cloud and then export it. Do so by completing the steps below:
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Select every scan and then right click > Filtering & Clustering > Make single cloud
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The new cloud will appear in the Unstructured Point Clouds layer
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Right click this new single cloud and choose Export > Save copy as > e57 extension. Remember where you saved it!
Autodesk Recap
The last step is to convert the e57 file in to the Autodesk Recap format. This will allow you to bring the model in to various Autodesk software.
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Open Autodesk Recap.
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Select new project > select scan files
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Navigate to your e57 file, select it an then select Open
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Select Next > Start Import
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Below is a screen shot of the final model in Recap.
Revit
After completing the Recap files, we then exported them into Revit. This allowed us to trace over the elevations and floor plans in order to create 2D line drawings. Below are the sheets that were created along with basic dimensions. Architectural drawings like these, are one of the final steps of documenting a building and help to provide accurate measurements in case the chapel succumbs to natural or man-made destruction.
Floor Plan
Elevation
Mausoleum Elevations
Floor Plan
Floor Plan
Elevation
Mausoleum Elevations
Floor Plan
St. Helena Chapel of Ease
St Helena Island, SC 29920
3D Laser Scan Screen Shots
Revit Floor Plans and Elevations
Below are the final images of the completed project using JRC Reconstructor and Revit computer programs.The final product included a 3D digital model and a set of plans for the church and mausoleum structures. Unfortuantely, this web site does not support the technology needed to import a 3D model. A further explanation of the process is located underneath the images.