Home Improvements: Random Prim Drift in a Large Build

Location: Caulking Seams

It's ironic that I talk about this on a day when, in real life, I need to caulk a seam between our house and a not-so-well-made addition. The building settles unevenly, and mortar joints love to crack. Good-quality exterior masonry caulk stops those cold drafts.

But there's no HGTV for avatars (though Prim Perfect comes closest). Even that fine magazine focuses more on style and design and not repair and renovation.

Renovation? In a fake building? Should be as simple as deleting prims or moving them, right?

Viv Trafalgar and I were touring the Second Life House of Usher in the guise of Madeline and Roderick, in order to shoot Viv's machinima I featured here a few weeks ago. I noted a rather large gap in a wall, and Viv, ever the master builder, noted that large builds do that. Elements creep apart over time. I don't know the reason; perhaps it's an infinitesimal rounding up or down when linked prims overlap ever so slightly. There's a JIRA at the Linden Lab Web site about this.

Torley Linden, who cares and knows a lot about technical issues in the code, asked a resident to give examples or reproduce the problem so Linden Lab could investigate. Here's a technical but vexing reply from Khamon Fate:

 It's a floating point error that is seen nearly every time one edits a prim's location, rotation, cut et al by the numbers. Type 35 degrees Y rotation into a prim and watch it magically adjust itself to 34.97 degrees. Doesn't seem like much really, but when that same calculating error occurs as the sim places, and replaces prims, they seem to drift. Those same miscalculations cause textures to be suddenly offset. The list goes on to include misplaced telepoints, odd ground configurations and really just anything the server has to manage mathematically.

It's a deep, fundamental problem in the server code and really must be fixed for these types of problems to be resolved.

I have not noticed the math error in our SL or Jokaydia Grid build, but I'll try an experiment of noting the position of some prims and then checking with my next log in. And, yes, it happened at Jokaydia Grid too. I found that a linked set of prims for Usher's interior walls had crept away slightly from some unlinked parts, including doors and "headers" over them.  Fixing that was easy--I had to realign the doors' headers and match the texture to the main wall's settings. Then I linked them.

As I did this, I was reminded of another "101" lesson: don't link scripted items to the linkset. I know that when I blogged about making a fireplace; the scripted prim needs to be the root. So I left doors and chimneys unlinked and floating free, as the rest of the House drifts.

My fix is to link the entire House in a few segments: roof, interior walls, exterior walls, crypt. I can then tweak each one a few hundredths of a meter to re-align the ancient manse.  If only it worked so well, on a cold December day, on a brick-and-mortar home!

My posts on building in virtual worlds are aggregated here. Happy home improvements!

Virtual House of Usher: Viv's Machinima

Location: Brooding in the Crypt

As part of an article Viv Trafalgar and I are co-authoring, she produced a video of our soon-to-vanish Second Life build of Poe's House of Usher. Many thanks to Jake Rose for composing an original theme for this video.



It's delightful to record the feeling of the House and more delightful still that an editor for an academic publication wanted machinima and still images in an online article. The scholarly world does change, slowly, and some things cannot be fully apprehended in print. Poe knew that; his most evocative work often stretched language to its limits.

A I watch Viv's video, I sense how much I will miss aspects of this House, and of course the wonderful content by builders such as Morris Mertel and several Steampunk geniuses.

We'll have a new House in Jokaydia Grid next year, ready for another group of students to try to save Madeline from her brother, and Roderick from himself, in an immersive re-imagining of Poe's shadowy masterpiece.

Touring Heritage Key Using Explorer HUDs

Location: Ancient Egypt

For some time, Viv Trafalgar has been after me to come back to a few regions in Heritage Key to see how the HUDs now available enrich an explorer's encounter with the past.

I have to say, these were just what I'd have wished to have for The House of Usher roleplay with my classes last year. The easy-to-master interface, shown here, provides a number of tasks for the adventurer. When all of the tasks are complete in a section, the explorer gets a prize.

Using the HUDs

I began at Amarna, and the HUD told me to visit several sites. For this part of the experience, Viv gave me a primer on the current version of the HUD (here's a sample from the Valley of the Kings):


Viv: each tab - uncover - envision - explore
Viv: has a quest attached to it
Viv: the first is finding four clay tablets, another is doing tasks around the household.
Viv: when you do [all the household tasks] you get a ring that lets you dance like an Egyptian

I began at the river's edge, where, upon clicking on the reeds, I began to gather them. This led to my first task's completion, and I learned something about how the ancient Egyptians used the river, as well as its flora, to sustain themselves.

Being the mummy-hunter that I am, I had to send the avatar to Valley of the Kings, where a HUD can be found at Howard Carter's camp. I'd already gotten a mask of Anubis on a prior visit, after figuring out the hieroglyphics in the mural room (with some hints from Viv).

I explored for some time, getting four of Carter's missing journal pages. I also got a stylin' bead necklace.

There's more to the HUDs than prizes, however:

Viv: at the top, there is a map button and a 'small' button
Iggyo Heritage: very nice for a first effort! Having a Web page in the viewer...familiar metaphor
Viv: clicking 'map' will pop up an aerial map


Viv: that will go away when you click it
Viv: click the envision tab so quests are explained
Viv: but they are also logged so visitors can engage in multiple quests simultaneously. There are more suprises on the way, too.

The Valley of the Kings has grown in scope since my last exploration. I found more useful interactive features, like this display about Harry Burton's role in the excavations.



Other objects loaded web pages (here's an example) from Heritage Key's rich library of 2D Web materials.

Other clues have to be unearthed, and when they do, some of them provide links to videos or other content to help solve the riddles of the architectural site. In this video linked to a clue I dug up, Fiona, 8th Countess of Carnarvon, gives a tour of the recreated tomb of King Tut at Highclere Castle.



How HUDs deepen immersive learning

As much as I love these Web links, it would be richer for students--if the speed of streaming the content permits--to have these materials inside the Heritage Key experience.

Viv and I talked about how the sort of in-world experience (as opposed to popping up Web sites) deepens learning:

Viv: it was important to have a way for people to reflect on what they did - inworld, not just on a webpage ... that breaks the immersion
Iggyo Heritage: this is brilliant

The hard work of many hours by Rezzable's team shows. All in all, I could have spent many more hours just at the Valley of the Kings. It promises to provide the sort of learning about Antiquity that cannot be done with a textbook or film alone; the immersive simulation brings the Tut dig to life.

Heritage Key content rezzes faster than before, though there is still some lag as pages of Carter's journal loaded for me. That would prove frustrating for students, and I was on a hard-wired connection with a very fast and new laptop.

Now I'm laying my plans for bringing some of this technology to my own pet projects.

For Usher, I could see the HUDs being customized so that the friends of the Ushers might each wear a different one, depending on their roles in the story. One of the group might have to look for medical clues, and when finding them all, s/he might discover a text on Chloral Nitrate, a drug that we decided would have been used to treat the sort of narcolepsy Madeline suffers. Then the student would know that Roderick had been giving his sister too much of the substance, sending her into a coma. A different HUD would lead the student to find the hidden passages and passwords that Roderick uses (and forgets, in his madness) to parts of the House that reveal secrets.


In an interview with AJ Brooks that I'll soon publish here, we agreed that virtual worlds, given the current state of higher education, will remain a "niche" technology. Content such as Heritage Key's merits a larger audience, and the company's initiative with Unity's Web-based viewer may get them the audience they want.