Calculating the Dimensions and Radius of a Curved Lithophane Created Using 3dp.Rocks

 

This article is in response to all the requests I have seen on Facebook, asking how to easily calculate the radius of a curved Lithophane created using http://3dp.rocks/lithophane/. This information can then be used to create custom enclosures. My first attempts at making this calculation consisted of printing the curved Litho and then measuring the straight-line distance between the two curved ends, called a chord. Because I was creating Litho’s with a ninety-degree angle is simplified the calculation greatly, since the chord became the hypotonus of an equilateral right triangle. The radius equals the chord divided the square root of two. If I had chosen any other angle I would have had to measure both the chord and the distance between the chord and the highest point on the arc. I would then plug the numbers into a slightly more complicated formula that you can lookup on Google if you want to know more about it.

There is a problem with this method of calculating the radius, you must print the curved litho before designing the enclosure. Plus making accurate measurements can be a pain in the proverbial butt. After much though I believe I have figured out a way to calculate the necessary information to create the enclosure without printing the Litho first.

When creating a custom enclosure for your curved Lithophane you need to calculate the unknown dimension of the Litho and its radius. The unknown dimension represents the length of the shorter side of the Litho image in millimeters. The longer side is set by the Maximum Size option in 3dp.rocks Litho model settings. These settings can be calculated in three steps.

Step 1.  XnView

The first step is to download and install a program like XnView. XnView is an application that I have been using for many years to read, view and process images. It is available for Windows, Linux, and OSX.

This program will provide the necessary physical dimensions in centimeters or millimeters of the original image that is being used to create the Litho, depending on the version of XNView installed

  1. Open the image that you are going to convert to a Lithophane.
  2. Select the View -> Resize menu
  3. Under Print size change the measurement to cm or mm.
  4. Record the Print size Width and Height values to be used in your calculations.
  5. If the measurements given are in cm then multiply each number by 10.

Step 2.  Determine the new dimensions of a Lithophane created in 3dp.rocks

Original Ratio Calculation:

Use the appropriate formula depending on the shape of your image. Remember that the Maximum Size setting determines the length of the longest side of the image.

  • New Width   = (Orig Width * New Height) / Orig Height
  • New Height = (New Width * Orig Height) / Orig Width 

Example:
Using the example numbers in the above XnView image we can calculate the new heights of the Litho if the Maximum Size is set to 100mm.

           New Height = (100 * 1066.77) / 1422.35 = 75.00 mm

Step 3.  Determining the Radius of the curved Litho

Two values from 3dp.rocks are needed to make the radius calculation. Maximum size and Angle value. Plug the values into the formula below to calculate the needed radius.

r = Radius of arc
a = Length of arc (Maximum Size value from 3dp.rocks or calculated width)
θ = Angle of arc (Curve value from 3dp.rocks)
π = pi (3.14159)

Examples:

Using the same Maximum Size value, the radius can be calculated any size radius.

60 degrees -> r = (180 * 100) / (60 * 3.14159) = 18000/188.4954 = 95.49 mm
90 degrees -> r = (180 * 100) / (90 * 3.14159) = 18000/282.7431 = 63.66 mm

Real World Considerations

Due to the dimensional inaccuracy that can plaque 3D prints there might be slight a variance in the printed size and therefor radius of the Litho when compared to the calculations. When comparing the measurements from my existing printed curved Lithos to my calculations I found up to a two mm increase in the printed width and height. This may be due to printer calibration and/or filament type. I am using eSun white PLA on an Original PRUSA MK2S. I also suspect the size and shape of the printed Litho will also determine the size of the variance. I measured a few of my smaller flat Lithos and the calculations were nearly perfect. I have not yet printed a curved Litho under 200mm so far so have not tested this theory in that scenario.

I want to warn everyone that my math skills are very rusty so if I have made any mistakes or there is a simpler way to accomplish this task please let me know. This process came to me in a moment of inspiration and appears to work better than I expected. Hopefully it also works for you.

Talk of the Town Podcast: Staying Safe Online #14

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my 14th visit to WHTC 1450 AM/ 99.7 FM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s
http://whtc.com/podcasts/talk-of-the-town-today/99/staying-safe-online-james-allen-aug-23/

The Importance of Updates

No matter what device you are using, keeping the hardware and software up-to-date is very important to minimize security problems. New security flaws are discovered every day and often affect devices that are no longer receiving updates. The most common devices include computers, phones, and tablets that do not support the latest operating systems. Other devices that most don’t consider are printers and other similar peripherals along with Internet of Things devices that are becoming more prevalent in our daily lives.

Once phones and tablets are no longer receiving updates they should just be replaced, even if they seem to still work fine.

If you are an Apple desktop or laptop user, make sure your computer can handle the latest version of OS X, soon to be version 10.13 (High Sierra), and if it does then follow the instructions on Apple’s support site on how to update your software. If your machine is no longer supported by Apple then consider replacing it with a new one or installing a version of Linux which often works well on older systems. This will extend the useable life of your machine and still allow to to keep it relatively secure.

Despite all the complaining about Windows 10, it is actually very user friendly and secure operating system compaired to it predecessors. If you are truely worried about being “spied” on by Windows 10 then you need to reconsider owning any device that connects to the Internet or become hardcore security savy quick. Windows has an update utility that will keep your Microsoft software and OS up-to-date, but the best way to keep your non-Microsoft softare at the latest version is to use a program like  Secunia PSI.

If you are a long time linux user then you are most likely very familiar with how to keep your computer up-to-date, but you do not have to be a hard core computer geek to reap the security benifits and flexability of Linux. Other than the security benifits, many flavors of Linux will give your older hardware a new lease on life while maintaining a decent level of security. Depending on what distribution of linux you choose, some of them try to mimic Windows and OS X interfaces and controls, which simplify your learning curve. Check out this link for more information: Best Linux Distributions for New Users

Remember that staying secure requires more that just updates. This is just one step closer to staying safe online.

Don’t believe everything you hear in the news about security hacks

Two recent sensational headlines that swept the press have been taken out of context. It is what we like to commonly refer to as Clickbate. Sometimes it is on purpose, and other times it is out of ignorance of the subject being reported. The two stories in question are about DNA being used to hack computers and Graffiti being used to confuse and misdirect autonomous cars.

Both of these items are not currently real world problems. The goal of the researchers was to find potential weaknesses in current technologies by using highly simplified models of the actual technology.

If you truly want to know more about Hacking and security related issues that have the potential of affecting your life then find news sites specializing in security related news.

  • http://www.krebsonsecurity.com/
  • www.darkreading.com/
  • https://threatpost.com/
  • http://www.securityweek.com/
  • Use your favorite search engine for many more security news sites.
Potentially new security feature in IOS11

In the very near future Apple will be releasing its newest version of its IOS mobile operating system, IOS11. A small subset of users have had the oportunity to test and review the beta versions of OS11. One of the newest features introduced a new hidden feature. By pressing the power button rapidly five times a screen will appear with an emergency call option, along with disabling the Touch ID and requiring the users to retype their password. The value of this new feature is two-fold. First, It provides a quick way to gain access to emergency services. Secondly, if you can activate this feature before law enforcement seizes your device, then they will not be able to compel you to unlock your phone using the password legally. Check out this Gizmodo article on the subject for more information.

You do not have to own a computer to be at risk

As Ubiquitous as Internet enabled devices are in today’s world, not everyone has one or uses it to buy things or do their banking. Despite this fact, there is still a risk of losing control of your credit cards and bank accounts. The first issue is the US Postal System, starting with your mailbox. Mail theft from unsecured mailboxes can be profitable for local thieves. Checking account information and Credit Card information is readily available, and you announce that fact when lifting the flag on your mailbox.

Some simple recommendations to protect your payments include using a secure mailbox. The second option is to drop your bills off at an official US Post Office mail drop instead of putting them in your mailbox at home.

Another security problem is just the act of using your Credit Card in public. Every time you swipe your card through a possibly compromised reader or hand your card over to an employee at a restaurant. These examples are just the tip of the iceberg of what can happen with your credit cards. The ways to minimize the threat are far too numerous to review here, but at the very least watch your bank and credit card accounts carefully and if you see anything out of place report it immediately to the appropriate bank or credit card company.

LastPass password manager

Near the end of the radio segment I mentioned a useful feature of my favorite password manager, Lastpass, One Time Passwords (OTP). OTPs allow you to create a series of random passwords, that you print out and store in a safe place, that will allow your to access the account once before it expires. This is a handy feature for several reasons. The first is when you want to log into your lastpass manager from a machine that you do not trust or suspect may have malware on it. The second purpose is to give you access if you temporarily forget your mainpassword. Lastly, and most importantly it allows someone to access your account and gain access to all of your accounts after you die. Create a OTP Password, print it out and place it in an envelope with the statement, “Only open upon my death” or something similiar. Now either put the envelope in a safety deposit box or give it to your attorney. Make sure someone is aware that the safety deposit box exists. For more information read the following article from lynndye.com.

Tools to help you keep your machine healthy

During one of the news and comercial breaks, I spoke with a caller. He asked me what he could do to better protect his machine. Though there are many ways to try to keep a Windows computer healthy.

  1. Do not run a third party Antivirus if you are using Windows 10. The built-in Defender program works well enough and you minimize your chances of being infected by malware that is designed to use third party antivirus’ to gain access to your machine. I know this does not completely make sense, but trust me on this one or do a little research to find out more.
  2. There are a few free third party security programs that are worth running occationally, but only in manual mode. Maybe once a month.
    1. Ccleaner: Eexcellant utility used to do basic cleanup of temporary files and the registry. This program can also be used to do a complete removal of unwanted programs from your machine.
    2. SuperAntiSpyware: One of the most effective utilities for finding well hidden malware on your machine. Only run full scans for the best results.
    3. Spybot Search and Destroy: This program a couple of useful functions. One is a spyware scanner and the other is a database of some of the known malicious websites that will be installed to protect your machine.
    4. Use the free versions of this program and disable any program that these applications may have set to run at startup.

There is more that can be done, but this is a good start along with keeping the software and operating system up to date and mentioned above.

 

Talk of the Town Podcast: Staying Safe Online #13

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my 13th visit to WHTC 1450 AM/ 99.7 FM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s 
http://whtc.com/podcasts/talk-of-the-town-today/99/cyber-safety-with-james-allen-july-26/

Adobe Flash End-fo-Life

Over the next three years, the once ubiquitous Adobe Flash player will be phased out of existence in a number of steps. The evolving HTML 5 standard and supporting technologies replace Flash in showing video and web-based game play. Why should you care? Hackers love to exploited users through their Adobe Flash plugin or fake download, when a site asks you to update to the latest version.

MySpace’s Zombie Data

Nearly half a billion past users’ personal “zombie data” still exists on their site. This realization comes in the wake of last years MySpace hack that claimed 427 million passwords that were then made available to buyers for $2,800. Even if you login was not compromised in last years password breach, MySpaces’ password recovery system is poorly implemented. At first glance, the recovery system appears to go overboard on the information it asks you to provide, but behind the scenes, the recovery process only requires three or more of the answers to be correct for you to successfully recover your password.

Solution: Delete your account and then change the password of any site that you may have used the same password.

Ad Blocking

Do targeted ads drive you nuts? Targeted ads are those that keep showing up after visiting specific websites or search specific topics. It can really spoil Christmas shopping online. The real problem with rogue ads that pop-up in the middle of your page, or those that contain malware that attacks your device while visiting a normally safe site. Plus limiting adds decreases bandwidth usage on mobile devices.

Before installing the nearest Ad Blocker consider the sites you are running it on. Does it the site have obtrusive ads? Do you visit these sites regularly? Advertising is often the only form of income some of these sites have. If you indiscriminately block all ads you could be a part of your favorite websites demise. Consider White Listing sites you want to support.

Talk of the Town Podcast: Staying Safe Online #12

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my 12th visit to WHTC 1450 AM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s show:http://whtc.com/podcasts/talk-of-the-town-today/99/updates-passwords-ai-james-allen-june-21/

New Password Guidelines by NIST

These guidelines are optional, yet often used, for non-governmental organizations. 

  • Three of the more relavent new password rules:
    • No more periodic password changes – Many organizations and some websites often require frequent password changes to the frustrations of users. This new ruling eliminates this requirement. This does not eliminate the need to change passwords when a breach is suspected.
    • No more imposed password complexity – The need for a password to have at least one lower case and upper case letters, a number and special characters is no longer a requirement. This does not mean that you are safe to use simple passwords.
    • Mandatory validation of newly created passwords – In order to make up for the recinded complexity requirement, new passwords need to be validated against a large dictionary of known, easily hackable, passwords such as 12345678 or Pa$$w0rd.
  • Password length is still critical part of a good password, the longer the better, with a minimum of 8 characters.
  • The use of multi-factor authentication, is an important way to increase the strengh of a user name/password.

Electronic Restrictions on Airlines

“Why we can’t have nice things” (or take our nice things traveling with us)

  • These restrictions only affect flights to the United States and Britain passing through ten airports located in eight Muslim-majority countries.
  • Israei Cyberoperators infaltrated a small cell of extremist bomb makers working t0 create explosives that could pass through x-ray machines and other screening methods, by looking exactly like batteries in laptops.
  • Cell phones are OK, but any electronic device larger than a smartphone has to be stowed in the baggage hold.

Microsoft Used Artificial Intelligence to Combat Global Tech Support Scams.

http://www.techrepublic.com/article/microsoft-used-ai-to-combat-global-tech-support-scams/

  1. Microsoft used AI to combat worldwide tech support scams as part of the FTC’s Operation Tech Trap.
  2. Machine learning was used to sort through content that was collected to determine if it was part of the fraudulent scams.
  3. The team also used Microsoft’s computer vision API to collect data like phone numbers from content associated with the scam.

Talk of the Town Podcast: Staying Safe Online #11

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my eleventh visit to WHTC 1450 AM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s show:
http://whtc.com/podcasts/talk-of-the-town-today/99/wannacry-and-beyond-james-allen-may-24/

Twitter Policy update

  1. Information about when you visit twitter are being stored longer. From 10 to 30 days.
  2. Changes are being made how and what type of aggregated information is bein shared with their business partners.
  3. Twitter will now ignore the Do Not Track option available in most browsers. This is not as big a deal as it sounds since very few if any sites honor the setting.
  4. Twitter has added personalized advertising. The change the way Twitter handles advertising you need to customize your accounts settings.
  5. To read more and see how to access and make changes to twitter, log into your twitter account and then click on the link in the title for more information.

WannaCry Overview

  1. WannaCry, spelling may vary, is a fast spreading piece of Malware that utilizes leaked NSA 0-day exploits to gain access to networks and spread without the help of human interaction, a.k.a a worm.
  2. Once WannaCry infects a machine it completes a few different tasks, non-good.
    1. Spends the first 24 hours seeking out, and attacking other computers on the network to infect.
    2. Encrypting user data and holding it for a ransom, to be paid in bitcoin
    3. Installs a backdoor on the computer to allow hackers to gain access to the machine anytime they want in the future.
  3. Most of the WannaCry infections occurred in Russia and China, due to a large number of unpatched pirated copies of Windows, but many other countries were also hit, including the U.S. with around a thousand reported infections.
  4. Windows 7 was the hardest hit by this infection, though that does not mean that other operating systems were immune.
  5. Microsoft released a patch for the primary vulnerability that was exploited in March, but due to many people’s reluctance or inability to install updates WannaCry still had devastating effects.
  6. If you are still using XP or Windows 7 make sure you update the operating system (OS) with the patches that Microsoft recently made available for the unsupported OS’. Check out this Youtube video help manually updating your OS.
  7. If you have been infected, your data may be recovered under very restrictive circumstances.
  8. No one has taken responsibility for these infections, but there are accusations and rumors flying around. Putin says the U.S. Created it and a number of security researchers believe that WannaCry has ties to North Korea, though definitive proof is still lacking.
  9. Check out the WanaCry FAQ link in the title for more information.

Talk of the Town Podcast: Staying Safe Online #10

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my tenth visit to WHTC 1450 AM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s show:
http://whtc.com/podcasts/talk-of-the-town-today/99/staying-safe-online-with-james-allen-apr-26/

Windows 10 Creative Update

  • The recently released Creative update to Microsoft’s Windows 10 is the first of two to be released this year.
  • If you own an older or low-cost Windows phone there is a 40% change that you will not be able to upgrade to the newest version of Windows.
  • New Features
    • Game Mode – Allows for better game performance.
    • Paint3D – An upgrade to the classic Windows Paint program.
    • Night Light – Allows you to use your computer at night without affecting your ability to go to sleep. Check out this article to learn more.
    • Dynamic Lock – Allows you to use your Bluetooth enabled phone to unlock your computer.
    • Edge Browser improvements
    • Start Menu now has folders
    • Greater Privacy – Microsoft gives you a little more control over what data they collect.

Google’s “Project Owl”

  • This is Google’s attempt to minimize fake news, disturbing answers and offensive search suggestions from appearing as a top ranked results.
  • New algorithms are being developed to make sure authoritative content pushed to the top of search results.

BrickerBot

  • A Vigilante worm that destroys insecure IoT devices.
  • Translated this means that there is a program that uses the Internet to seeks out your smart light bulbs and other such devices that are not properly protected and makes them unusable.
  • This is being done to prevent these unprotected devices from being used in DDOS (Denial of Service) attacks.

See you next month.

Talk of the Town Podcast: Staying Safe Online #9

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my ninth visit to WHTC 1450 AM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s show:
http://whtc.com/podcasts/talk-of-the-town-today/99/staying-safe-online-james-allen-mar-22/

5G is on the Horizon

Article #1
Article #2

The hype is on for the upcoming new cellular communication standard 5G. Its key benefit over the existing 4G standard, speed. Speeds up to 1 Gigabit/sec are possible though expect the average speed to be considerably less.  Don’t be in a hurry to replace your mobile device with the latest and greatest, because 5G devices will not be widely available for a couple more years. Even though limited deployment is currently in the final planning stages, the standard itself is not complete and is subject to change. 

The Newest Computers no Longer Support Older Operating Systems

Those of you who want to continue using Windows XP, Vista, 7 or 8.1 for the foreseeable future beware. If you currently own or are preparing to upgrade your computer hardware to one of the most current processors you will have to use Windows 10 or Linux. Microsoft has blocked updates to older Windows operating systems running on the 7th Generation Intel processors and equivalent processors by AMD and Qualcomm.

Cybersecurity Tips

Please read the USA Today article for details. Though I do have some concerns and clarification about some of the tips.

The article states, only use secure web browsers. This is a misleading statement. What it is saying is that you should only interact with websites that are secure, meaning they use HTTPS and they show a Green lock at the beginning of the address bar. In reality, you only have to worry about using a secure site if you are asked to provide personal information or making purchases on the site.

Talk of the Town Podcast: Staying Safe Online #8

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my eighth visit to WHTC 1450 AM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s show:

http://whtc.com/podcasts/talk-of-the-town-today/99/cyber-security-with-james-allen-feb-15/

Microsoft’s call for a “Digital Geneva Convention.”

Brad Smith, the president of Microsoft calls for the security community to remain neutral when nations fight each other in cyberspace.

Arby’s POS Data Breach

Arby’s corporate owned restaurant have had POS data breach of 335K records. 

Vizio has been watching you

Vizio has been caught and fined for collecting information on your viewing habits and selling it with a little too much info about you. If you want to disable the “feature” check out the linked article.

IRS Tax Scams (see article for details)

  1. Identity Theft
  2. Phone Scams
  3. Phishing
  4. Return Preparer Fraud
  5. Offshore Tax Avoidance
  6. Inflated Refund Claims
  7. Fake Charities
  8. Falsely Padding Deductions on Returns
  9. Excessive Claims for Business Credits
  10. Falsifying Income to Claim Credits
  11. Abusive Tax Shelters
  12. Frivolous Tax Arguments

Sorry for the short write up this month. I am preparing for the kickoff for the Davenport University Robotics Program.

Talk of the Town Podcast: Staying Safe Online #7

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my seventh visit to WHTC 1450 AM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s show:

http://whtc.com/podcasts/talk-of-the-town-today/99/held-up-for-ransom-more-cyber-security-expert-james-allen-dec-21/

Hackers vs. Yahoo

Over a billion user accounts in August of 2013.
http://mobile.nytimes.com/2016/12/14/technology/yahoo-hack.html

  • Time to change email accounts!
  • Change your password and security questions not only on Yahoo but other accounts that you may have used the same information.
  • Do not delete your abandoned yahoo account unless you want someone else getting a hold of it to cause mischief.
  • Create autoresponder email message to guide people to your new email address when they send something to the old account. (https://www.youtube.com/watch?v=oS4qKFgD59E)

“Popcorn Time” Ransomware

Personal Security at community events

Assume there is someone watching you at all times at these events. They are waiting to take advantage of the moment and take what does not belong to them. They are stealthy, and you may never know what happened. I was lucky that the thief was caught on video taking my bag with my laptop in it, the perps picture is now circulating, but there is only a very little chance I will see the contents of that bag again.

 

Talk of the Town Podcast: Staying Safe Online #6 – Holiday Scams

Welcome to HakProof.com. This site is my attempt to reach out beyond the physical classroom to the community at large to help each of you increase your personal SQ or Security Quotient.  Today was my sixth visit to WHTC 1450 AM radio station in Holland Michigan to be a guest on the daily show, Talk of the Town.

Click on Link to access the Podcast, of my time on today’s show:

http://whtc.com/podcasts/talk-of-the-town-today/99/cyber-security-with-james-allen-nov-30/

I promised the listeners to provide an outline of what we talked about today. Hopefully, you will also find the information beneficial.

Holiday Scams

Here is the original link to the list I spoke about on the radio.

‘Tis The Season To Be Wary: 12 Holiday Scams to Avoid

I won’t duplicate the article here, but I do want to stress the need to do a least a little research into your holiday opportunities to make sure you are not being taken advantage of. The fraudsters trying to steal from you do not share your holiday cheer.

Remember to use reliable services like Paypal or Amazon Pay to minimize the chance of credit card fraud and use a credit card instead of a debit card when needed so you will be able to more easily contest bogus charges to your account or to stop a transaction if you realize intime that you have been had.

One of the callers today spoke of loosing control of his email account for a period of time and not all his mail goes to the trash instead of his inbox. Below is a link that may help fix the problem:

  • This link has multipe sugestions for solving the problem if you are using gmail.