Metal Detecting in the USA

In the field. Notice the high contrast map and the battery case.

A year or so ago, I became familiar with Maprika – and used it for a long mountain bike trail for which I only had a paper map.  It kept me from getting lost!   It was awesome, putting your GPS location over the top of actual scanned in maps.  Even hand drawn ones.   I have used it on vacations, for zoos, and even on photos of maps taken in libraries!

Maprika allows you to load old maps, create reference points, and then accurately plot GPS location onto the old map.  When you’re in the field, you see yourself as a blue dot on the old map.  As you move, your dot moves – helping you to find house sites and such.

How it works is this, in a nutshell.

1. Check to see if the map you want exists already.  Go to Maprika’s site and click on available maps.  Zoom in and see what’s in your planned hunt area.  Someone may have already digitized the map you’re planning do do.
2. Download Maprika phone app from itunes or app store onto your smartphone or tablet.
3. Install the Maprika’s map building software on your computer.  This works better with large monitor if you have it.
4. Start with your old map.  Scan it, buy it, download it.  Make sure it’s a high resolution JPG or PNG file.  You can use maps you’ve photographed at the library too if you’ve done a good job keeping them clear and steady.
5. Convert the map to high-contrast (optional.)  Using your favorite image editing software, make the map monochrome and high contrast to make it easier to read in the bright sun in the field and save the file – this is the file you’ll load into Maprika.   RESOLUTION LOSS WARNING.  Make sure you don’t lose map resolution after adjusting it and re-saving it.  Higher resolution pays off when you zoom up.
6. Load the map to Maprika’s map building software- I do this on my desktop computer, but I think they have other ways.  The old map will go on the left, and modern Google Maps (I use Hybrid mode) will appear on the right.  IMPORTANT:  If you are editing maps you’ve already uploaded before, you MUST log in under the server menu using the same username/password that you used on your mobile device.  Once you upload a map, your username and password are forever attached to it so only you can update it!
7. Load up the modern map on the right. Use the “search feature” on the bottom right to enter cities, GPS coordinates or whatever so that your Google/Bing map is centered on the right.
8. Begin adding georeference points.  Once both maps are loaded and in similar orientations, click ‘new point” to start adding reference points.  First, put the point on the landmark on one map, and then find the same landmark on the right.  See illustration below for an example… <save often!!>
9. Finish Up.  After you have 50-100 reference points, save the map using “File/Save”
10. Fill in Map information, title, keywords Map Properties choice under the File Menu –  This is how you’ll find the map later.  Save the map again.
11. Publish the Map. Upload it to the Maprika server using the “Upload to server” menu choice.  Be patient on large maps.  It takes 3-4 minutes sometimes.DONE!  Now you’re ready to use the map  The map will then be PUBLIC and can be found by anyone else using Maprika.  I wish they had a private option, even with a fee.
12. Load the Map into Your Phone. Go and load the map covering the area you want to hunt – here’s where you’ll see the map info you entered pay off.
13. Head out into the field….It will then show your GPS position ON THE OLD MAP and you can zoom up tight, pan and so forth without any loss of clarity.  Sweeet.  You can find old houses and more this way – the sky’s the limit.
14. Enjoy! Let me know if it helps you!

Here are some tips:

Only load the maps you need.  I have found the iphone application gets slow and buggy if you load too many maps.  I have told Maprika about this.  I find it crashes a lot with more than 6 maps loaded.  (update: Maprika said they have done some fixes that may help on this.)

More points, the better.  I usually ended up with 50-100 points per map.  In areas where I knew I wanted to do a lot of hunting, I did more reference points.  I know it will make my field work more accurate.  In this example map – there are 102 points.  Save your file along the way!!

Maprika is the software that makes this possible.

Where to put reference points???  Use Road Intersections, Corners and Railroads to help you point..  See here that my points were at intersections and corners.  Every few minutes you spend improving the references can save you hours in the field.

Corners, Intersections and Crossings are great for reference points

Before you know it, you’ll be finding old routes for roads that are long gone – usually because of development, modern highways, railroads or other reasons.  Maprika allows you to trace the old map and watch the cursor move around on the new map.  It’s habit forming.

Use a Battery Case.  You’re going to eat battery juice with Maprika and GPS working fully time.  Good ones run around $40 on Amazon.

Right Mouse to Add Point.... When using the maps, you can use “right mouse” to start a new point.  This saves time!

Super High Res on the Source Map is better.  Make sure that you don’t lose any resolution along the way.  Bring in maps at the highest resolution you can get, even if they end up being 5, 10, 15mb in size.  I had some that were 8000×4000 pixels.  And they worked great.  If you’re scanning, scan at 300-400 dpi and see how that works.  If it’s not enough, ramp it up.   If you get a fuzzy image like the one to the right, you’ve done something wrong.  Go over your process and figure it out.  You CANNOT DO THIS with low-res or fuzzy maps.

Here is the hidden sweet thing about Maprika.  You get high res historic maps on the iPhone without it losing resolution.  This is one of the only ways to get large map images to stay full-resolution while you load on the phone.

Make sure you have high-res from start to finish. Experiment.

Converting your map image to high-contrast helps in the field.  When you’re outside in bright sun at a detecting spot, you don’t want colored maps – you want harsh black on white.  I used Photoshop to remove the colors and then increase the contrast on the maps.  In Photoshop this is pretty easy… just load in the high res map and adjust…

In photoshop or equivalent – convert to B/W image, then turn up the contrast

High Contrast makes maps easier to view on the phone/tablet screen in the field.

(Optional, but recommended) Align Map to North before you load it into Maprika.  I always rotate the map to true-north before loading it – just to make the process of plotting reference points easier.  Maprika’s developer told me that this was not required.  I think it’s up to you.

Here’s how it looks on the iPhone.   This map can be zoomed way up because of high resolution throughout.  As I move about, it will track me (blue dot) onto the historical locations.

If you’re using iPad, make sure to click on the 2x button to make Maprika Full Screen

1. Load map. 2. See map. 3. Your Location 4. Zoom

You can imagine how amazing this is if you scan old topographic maps, sanborns, etc.   I’ve gone scan crazy.

You can even take high res photographs of maps at the library and use those as the input and try to photograph it straight-on with a steady hand, and make sure the north indicator is visible.  It’s a big time saver!!

Get an external battery for your phone because GPS drains it.  I use a battery case.

Happy Digital Hunting!