123D Catch Floating Object Solution

Plain's pot sherd - in 3D!

Devin Hill, an archaeologist using 3D imaging to analyze plains pottery, sent me an e-mail and photos last night.  I was puzzling over the problem of holes in my Autodesk 123D Catch models last fall.  Devin came up with such a simple and effective method for fulling capturing an object using the software that I asked  if he'd mind sharing his method here.   He agreed:

Hi Tim,

I've been playing around with photogrammetry technologies for the purpose of creating accurate 3d models of artifacts, and only recently discovered that you've made some forays into this as well. I'm trying to do a Master's thesis on the feasibility of such technologies toward the analysis of otherwise unremarkable plains pottery detritus. I first tried Bundler Sfm. I've found the setup and operation of the open-source binary files to be ungainly and prone to all manner of error messages and mystical results. 123d Catch is superior to anything I've seen or used so far.

However, the real 'catch' is getting an artifact to float so that it can be manipulated in isolation (a common shortcoming of the photogrammetrical approach in general). I have no qualms with importing it into Blender or 3ds Max to do post editing, but this is a time sink and gets further from the source object with every tweak. I tried a number of things and have found a method that seems to produce a promising result. I thought you might benefit from my efforts as well.

A fully rendered floating object in 123D Catch

The trick, I have found, is to hang the object is some way (from a lamp in my case), taking pictures of the mid-section and underside of the object (a body sherd in my case). I am careful to avoid capturing the part of the object bound with sticky-tack. I usually do a test render to see how the first batch looks. Then I drop the object down onto a stable surface. I keep the object oriented exactly the same way, so that the light and shadow play on the surface of the object in a constant fashion. I think this helps the software immensely. I then shoot the mid-section again, then do a series around the top (again, avoiding the base of the object and the contract surface). Render and check for holes. Add additional photos as needed and hope for the best. My test-rig is fairly unsophisticated, yet the results are still very exciting. I think if I used a more contrasted backdrop, I could avoid a lot of the holes and glitches in the model, and reduce the number of patch photos I need to take.

Devin Hill's set up for capturing all sides and surfaces of ceramic artifacts.

I sincerely hope this helps you in your own experiments.

Devin Hill

PS. This technology blows my mind, even after spending considerable time playing with it. The archaeological applications are staggering really.

==========

Devin adds: "It would be nice if Autodesk would incorporate a mesh-merge feature of some sort, so that two separate renders of the same object could be combined geometrically, rather than photogrammetrically. Perhaps they just need someone to put that bug in their ear..."

So if anyone from Autodesk is reading this, here's an idea for an update in future versions.

Photo Credits: Devin Hill

Top 3 Digital Procrastination Ideas to Start the Week

Tilt-shifted Lourdes.

1. Unnecessarily Tilt Shift Old Photos.  Tilt shifting is when you blur the top and bottom of a perfectly good photo to create the illusion that you are looking at a miniature scene.  I found a good online site and iPad app for tilt-shifting photos.   Online, I've been playing with tiltshiftmaker.com, where you upload a photo, tweak it, and then save it.  Its pretty easy and has a nice range of options.  For the iPad, I used TiltShiftFocus.  I think I prefer the iPad version, although I don't have as many photos to play with on the iPad.  Tiltshiftmaker is free and TiltShiftMaker cost $1.99.

Tilt-shifted Alberta badlands

Slightly tilt-shifted Esco, Spain

I don't know if this is really tilt-shifted, but the vignette blurring was done in TiltShiftFocus on the iPad

2. Learn about Caribou Fences.  Caribou fences were complex wooden features designed to funnel and trap herds of caribou by arctic and subarctic hunters.  Caribou Fence Interactive is a fantastic site out of the Yukon that illustrates the construction, use, and archaeology of caribou fence systems in northwestern Canada.

3. Make MagicPlans.  This is something that I plan to spend a lot more time procrastinating with, because I think it may have archaeology mapping applications.  MagicPlan is a free iPad/iPhone app that lets you construct accurate floorplans using a series of photos that you take in any room.   Its designed to help arrange furniture and create real estate floor plans.  But it seems so quick and easy and accurate that I think it could be used in archaeology to record features, especially on historic or industrial sites.  I've really only played around with this in my house and it mapped my bedroom accurately in a couple minutes.  An archaeologist friend used to to map his backyard.  I'd like to take it around to some of the historic buildings and foundations sprinkled around St. John's and see how it works to record features.  One weakness that I can foresee is that it assumes a horizontal floor surface, which may not always be the case in an archaeological feature - still, I think its worth exploring and experimenting with.

Photo Credits:
1-4: Tim Rast
5: Screen Grab from Caribou Fences Interactive
6: Screen Grab from MagicPlan Website

Tci-tho - an Athapaskan bifacial scraper

An un-ground bifacial slate scraper

So this is kind of cool - I learned about a new type of artifact this week.  One of the artifacts in the Cape Krusenstern collection is a tci-tho slate scraper.  I hadn't heard of them before, but I did a little digging and apparently the name comes from hide-working tools used by Athapaskan peoples, who are spread over the northwestern part of North America.

Rounded working edges

I really need to emphasize that I don't really know anything about these tools other than what I've stumbled across online in the past hour or so and the reference photos that I was sent from Cape Krusenstern.  My first impressions might be off, but I found a couple references to tci-tho and tci-tho-like bifaces in Matson and Magne's 2007 "Athapaskan Migrations: The Archaeology of Eagle Lake, British Columbia: Appendix I".   The reason I found that reference interesting was that it mentions that a couple of the tci-tho-like bifaces tested positively for blood and fat residue, indicating that they were used for "flesh or hide processing".

A loose leather grip? Maybe?

The circular slate disc that I was asked to reproduce from Cape Krusenstern doesn't have any obvious signs of hafting, although this image of a stone scraper from the Bata Shoe Museum's online exhibit called; Tradition and Innovation: Northern Athapaskan Footwear shows a nearly identical slate disc, partially wrapped in cloth to create a grip.  The scraper in the Bata image has a little more polish on the edge than the disc I'm working on, but otherwise its pretty much identical.

Photo Credis: Tim Rast

A Set of Maritime Archaic Artifact Reproductions

Maritime Archaic Reproductions

Here's a look at the complete set of Maritime Archaic reproductions that includes the bird bone flute and hafted adze that I highlighted on Monday.  These reproductions will be used in conjunction with some original artifacts and interpretive materials in the Red Bay and Gros Morne areas.  The artifacts that we started with for references included stemmed points, an adze, and a plummet.  The remainder of the reproductions are primarily based on artifacts found in the Martime Archaic burials at Port au Choix.

This is an archaeology case used in a programme that I provided reproductions for a few years ago.  The pieces shown here will help build and expand on the programme.

Slate Lance for Sea Mammals

The Archaic period in Newfoundland and Labrador is a lot more complex than I usually give it credit for on this site.  Generally speaking, the Archaic period in North American archaeology is a time starting 7 or 8 thousand years ago when people seem to have settled down in different regions and developed specialized tool kits for those particular regions.  During the Archaic period in Newfoundland and Labrador people adapted to exploiting marine resources - so it was labelled the Maritime Archaic.  However, there are differences in artifact types and materials through time - the Archaic period spans at least 3 or 4 thousand years in the Province.  There are links and commonalities with Archaic sites in the Maritime Provinces and New England.

Plummets.  These are often made from Steatite (soapstone) and are carved with an incised groove at one end or around the middle. They seem like fishing gear - probably line sinkers.  They could have been used on nets, although I don't think they are found in big enough numbers and they are relatively small.  I believe there was an Honours thesis done at MUN a few years ago that looked at their distribution and form.

Toggling and barbed harpoon heads - like the this one - show up in the Maritime Archaic as part of the regional adaptation to the marine environment.  

People were buried with bird-head combs

There are differences between the Archaic sites found in the southern part of the Province, and more northerly parts of Labrador, so archaeologists have talked about a Southern Branch of Maritime Archaic and a Northern Branch or Labrador Archaic.  Dominic Lacroix is working on a Ph.D. at MUN that examines further regional differences or countries within the Maritime Archaic sites in Newfoundland.  The differences in preservation further complicate things.  We have unusually well preserved artifacts and mortuary remains for the Maritime Archaic in the southern part of the Province, but most of our information on dwellings comes from northern Labrador.  The Archaic sites are the earliest sites in the Province so they have been riding through thousands of years of sea level change which had submerged some sites and elevated others.

I guess its like anything else. The more closely you examine it the more complicated it becomes.

Throughout the Archaic timeline, triangular points were replaced with stemmed points.  The stems grew longer and then started expanding at the base until they became side notches.  That's a trend that happens during the Archaic more-or-less continent wide.

Hafted Adze, ground slate lance, barbed fish spear prong, unhafted adze, three projectile points, bird headed comb, barbed harpoon head, bird bone flute, plummets.  A person could probably have an ok start in the afterlife with a set like this.

Photo Credits:
1, 3-8: Tim Rast
2: Margaret McKeon

Maritime Archaic Flute and Adze

Hafted and unhafted adzes, flute, etc.

I'm packing up and shipping the Maritime Archaic Indian, Groswater Palaeoeskimo, and Recent Indian reproductions bound for Red Bay and Newfoundland's west coast later today.  We had nice sunny weather yesterday so I photographed the finished pieces in the backyard.  In this post, I'll talk a bit about the bird bone flute and the adzes in the set.

Goose humerus flute

For the flute, I used a goose humerus, because it was the biggest bird bone that I had on hand.  The Maritime Archaic Indians made a variety of flutes and whistles from the hollow bones of large birds including geese, gannets, swans, and eagles.  Ulnas seem to have been prefered, but other bones show up as well.  Most of the flutes and whistles that I'm aware of were found in the burials at Port au Choix.  I'm no musician, but I've talked to some people who are passionate about flutes and whistles - so hopefully they'll correct me if I get something wrong here.

blow across the top

This reproduction is a flute, meaning you blow across the opening to produce a sound.  A whistle is an instrument that you blow into the end to make noise.  The Maritime Archaic Indians made both.  In the case of a whistle, a slanted notch or hole is made somewhere midway down the shaft of the bone.  For a flute, you need to cut a small slanted notch in the end that you blow across.  You play it by blowing across the top, similar to how you make a noise blowing across a bottle mouth.  That little notch is important - it splits the air and creates the sound of the flute.  I wasn't aware of the mechanics of flutes the first time I made a Maritime Archaic bird bone flute and I though that little half hole was a crack in the bone where it broke through a finger hole.  That's not correct - it was intentionally made.  If you look carefully at the intact flutes from the province, you'll see a little notch on the end of every one.  If its missing that notch, look at the holes along the body of the instrument - one will probably have a slant edge to it, indicating that it was a whistle.

The end notch is important

I'm not a musician.  At all.  I was in a marching band in elementary school and they kicked me off the bugle and put me on baritone bugle because it had fewer parts in most songs and my errors were less shrill.  Then they took me off the baritone bugle and made me a flag bearer.  Still, if I blow on this flute and get the angles right I can get it to make a sound, especially if I keep my finger over the top hole and keep the bottom hole open.  The impression that I get is that smaller bones makes a more shrill noise, whereas those big wing bones from the bigger birds would create a lower, more pleasant sound.  I know that the baritone bugle was bigger than the regular bugle and it made a lower noise, so I'm guessing the same principle is at work here.

Adzes were woodworking tools

For the adze, I used a silicified slate or argillite for the bit, hardwood for the handle, sealskin for the lashing and ochre and oil, water, and egg for the pigment.  The complete adze will be there for the kids to pass around and handle, while the unhafted blade will be used in the mock dig.  For these sorts of stone tools, I like to leave traces of all the stages of manufacture in place.  Some axes, adzes, or gouges that we find in the province are perfectly finished and polished, but most have a nicely finished (and perhaps use damaged) bit end, but the rest of the body of the adze is more roughly shaped and usually show traces of chipping and pecking.  We don't find the wood handle or lashing, so that's a bit of guesswork based on other adzes from around the world.

The working bit on an Maritime Archaic Adze is usually the most heavily worked and finely finished part of the tool.  The rest of the stone would have been buried under lashings and wasn't as finely finished or polished.

Bit sits on a shelf, but doesn't butt against the back

The proximal ends of adzes are often irregular and I've sometimes wondered why they aren't more carefully finished.  It seems like they could be carefully shaped to butt up against the handle and create a more secure bond.  Robin Wood has been part of a team building a reconstruction of a Bronze Age boat and he made many of the woodworking tools used in the effort.  He noted in his bronze adzes that if the back of the bit made contact with the wood handle it would bounce loose during use. In Newfoundland, the Palaeoeskimos used antler sockets for their stone adzes to act as shock absorbers to prevent this problem, but I think that the Maritime Archaic probably just made sure that the back of their adze blades didn't make contact with the wood handle.  I've started leaving a gap between the distal end of adze blades and the wood handle in my Maritime Archaic reproductions now.

I have a lot of sealskin thong on hand, so I use it on reproductions like this.  Different sorts of leather or rawhide lacing could have been used as well as cordage made from plants or roots.  We don't get wood or leather preservation in Maritime Archaic sites in Newfoundland and Labrador, so we details of the handle and lashing are based on analogies with other adze using cultures.

A forked branch is used to make the handle.  I try not to get stuck in a rut when I make reproductions like this.  Since I 'm speculating on the style of handle, I like to change things up - maybe someday I'll accidentally make one that is correct.  For this particular adze, I left a longer knob opposite the bit end and covered the whole thing in red ochre.  I'm happy with it.  I think if I sent it back in a time machine and someone in a Maritime Archaic camp tripped over it they'd wonder who left that there and not "what the heck is that thing?"

Photo Credits: Tim Rast

Wrapping up the Week

Bird combs, ready to ochre

Today, I'm working on the last of the reproductions bound for teaching kits and a mock dig at Red Bay, Labrador.  Its primarily Groswater Palaeoeskimo and Maritime Archaic Indian reproductions, although there is one Recent Indian arrow in the mix.  The arrow is done and all of the Groswater reproductions are finished, except for the lashings and line on a harpoon.  

Grinding the ochre

The Maritime Archaic pieces are all finished, except for the ochre.  I think I'll ochre all the archaic artifacts reproductions this time. I still don't know if things like adzes or projectile points would have been covered in ochre when they were in day-to-day use, but it does help make the reproductions look cool.  It also creates a talking point for interpreters.  My pet theory is that ochre and grease on tools in this damp part of the world was a waterproofing agent that would help prolong the life of the objects that they coated.

Patty and Bjarne and whalebone

It would be simple enough to test a theory like that, I just need to get organized enough to come up with an experiment and do it.  Perhaps what I need to do is plan some purely experimental time into my yearly workshop schedule, rather than try to tack the experiments on to regular Elfshot work.  I alluded in Wednesday's post that I wanted to get a little more organized about the experimental archaeology side of the job. While Bjarne Grønnow was in town earlier this week for Patty Well's Ph.D. defense (passed with distinction - congratulations!) I had a chance to hang out while the two of them and Priscilla Renouf went through some of the organic Dorset artifacts from Port au Choix. There's a place for making reproductions and playing around with them to see how they work and what their limits are, but Bjarne encouraged a little more systematic and rigourous approach to experimenting with reproductions.  Hopefully, more on that later.

Groswater harpoon assembly

Anyhow, for now, I'm wrapping up one order in the workshop and moving full time into the Cape Krusenstern reproductions next week. I'll probably post a few more shots of the reproductions bound for Red Bay once everything is assembled, stained, and dried.  There are one or two pieces in there that I have never made before, so it was fun for me.

Burning blubber inside a Choris pot for Cape Krusenstern.  I want to stain the inside of the pot  with grease as much as possible before breaking it apart into sherds.  A big hole blew out in the side above the flame not long after this photo. Oh well, it has to come apart somehow.

 Photo Credits: Tim Rast

500th Post

500 pages in and counting

I started this blog in February 2009 and quickly settled on a routine of publishing posts every Monday, Wednesday and Friday. I've stuck to that schedule ever since and this post is number 500. It seems like a milestone worth mentioning. According to the initial post, I planned to use the blog "to keep a record of the work I'm doing now and in the future."  The site has evolved a bit since then, but that is still more-or-less its purpose.  Maybe that goal should change or expand.

Monthly stats for Elfshot: Sticks and Stones since August 2009.  Currently, the site averages just over 10,000 Page Loads and just under 6,000 Unique Visits per month.  Over the course of a year, visitors seem to go up in the spring when I'm in the workshop and posting  about new projects.  Folks wander off during the summers while I'm in the field, and slowly rediscover the site in the fall.

Most people are here for wolfkillers

I'm nosy about other bloggers' stats, but I don't think I've ever shared mine here.  Blogger has built in statistics which came online a year or two ago - that's how the sidebar section called "Popular Posts" is generated.  There are different display options for Popular Posts, but the ones regularly displayed on this site are the most visited pages in the past month.  I like that option because it usually shows a mix of new and old posts and changes a few times a week.  But I can also see what the most popular posts are from the past day, week, or all time.

The Three Most Popular Posts of All Time are:

1. Baleen Wolfkiller: Fact or Fiction?
2. How does a Thule Harpoon Work?
3. Patinating Copper Experiments

Before Blogger started tracking site stats, I began tracking statistics with ClustrMaps and StatCounter.  ClustrMaps says that the site has had 91,033 visitors since March 2009.  StatCounter says that there have been 194,093 page loads since August 2009 and 111,069 unique visitors since August 2009.  I'm not sure why StatCounter lists more visits in less time, but I suspect that ClustrMap may have more strict filters for weeding out revisits from the same user or IP address.

Puzzles like this foreshaft keep me going

So has it been worth it?  I think so.  I've learned a lot from the comments that people leave and the discussions that arise from the posts.  I use the site frequently as a notebook of past projects to check back and see what worked or didn't work.  I've been contacted by colleagues and strangers who let me know that some photo or discussion on the blog was useful to them or their students. I've reconnected with old friends and family because of the site.  New clients have contacted me because of work that they've seen on the blog.  I know that I'm pretty lousy when it comes to presenting or publishing my work in more conventional and scholarly forums, but at least some of the observations and ideas are being preserved and presented until I can work them into papers or publications that are a little easier to cite. In preparing this review post, I've realized the value of keeping this type of open notebook, but its starting to feel like a closet full of field notes that have never been properly written up or published.  I feel like I should do something more with it all.  I think that should be my new approach to the site during the next 500 posts.  I'll keep doing the work and recording it here, but I want to make more of an effort to get the ideas off the blog and into some more conventional formats that are a little easier for other archaeologists and experimenters to access and evaluate.

Photo Credits: 
1: Eric Walsh
2,4: Tim Rast
3: ClustrMaps