Georeferenced PDF maps (from Geovic or elsewhere)

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Howdy,

Some great topics in this Maps and Resources forum. Some of the topics relate to this so I thought I would post a thread about what I know and have been using for a few months now (as a geologist and newbie prospector with a GPX 4500 and very little gold to show for it....yet).

There is a few ways that you can create georefenced maps - after many failed attempts at running down rabbit holes with different software packages I stumbled across a free way of doing this.

For those that don't know a georefrenced image (pdf or tiff etc) has a signature attached to it which places it in space, effectively a global reference point, so when utilised in certain apps or software on things like (location services enabled) iPhones or IPad you can see your actual live position on the screen. Similar to how Hema topo map products work on various platforms. The difference being that you can create these maps yourself after exporting (pdf print function) on Geovic (or other maps from other sources) to create an image, that can then be georefrenced and used on your iphone.

Have successfully been utilising this around central Victoria with geovic outputs of mineral occurrences, topographic 1:25000, shafts, workings, public land boundaries etc etc and typically it puts me dead on the spot along tracks, at shafts etc. Good for traversing, pin pointing, preparing target areas at home which can then be chased when you get to the field.

This is going to take a few messages to cover it, as too much info to put in one sorry. Really just gauging levels of interest to continue before I spill the beans - people want to hear about this?

cheers,
Fever.
 
Sorry - to wet the appetite I thought I would post links to the software packages. The education (and frustration) then follows:

Iphone/pad app that I use to import maps to is by avenza and is called PDF Maps - tried to post a link, but forum wont let me because I am a newbie - just google it.

If nothing else you can just get that app and use some of the free stuff in there. I recently asked avenza to upload all of the parks victoria prospecting area maps - if you search in the app once you've downloaded it you can get these parknotes maps for free (plus many more) - and they are accurately georeferenced so can be used in the field.

I use this software to georeference images - Q landkarte gt, cant link it so look for the "sourceforge" website that has the software for free

There is an instruction page on how to georeference. Will need translation in to human speak, currently looks like robots constructed it. Google -
"Georeference_a_map" and "qlandkartegt" and "Sourceforge"

You will also need a software package like Adobe that can turn pdf's in to tiff images.

But that's a story for another day.

Fever.
 
Mate
I am willing to learn...
I am on the other side of the paddock...
There may be information I can use ....
Spill the beans as you say....

Cheers Nanjim
Jim
 
Good topic and work Fever, there are a few ways to do this and I have not tried this way yet. Remember a lot of the old coordinates used on maps use an old datum point and different measures. This can be confusing for sure. However once you have them mapped they work out as a very useful tool. Do you use metadata associated with the file or some other reference?

Old PDF/Jpeg maps can also be overlaid on Google Earth which is what I do then stretch and match the old map to the current satellite view. Then save it and you have all the correct data in place and you reference it on Garmin GPS etc now as a kml file.

To convert PDF's to TIFF and probably the best free photo editor you can get is the Gimp - http://www.gimp.org/ it is an amazing piece of software but has a bit of a learning curve but once you get the basics you can use it pretty easily to cut/crop and re-save an image.

Certainly keen to see how you do the uploads and conversions on old maps.
 
Thanks westaus- will give gimp a go.

Back tonight with some more info.

Fever.
 
Hey fever, great topic especially from someone that knows a bit about it.
I'm currently limited to just marking the spot in Memory-Map and adding a few comments (Date/detector/number of nuggets etc).
I also use GeoVic (2) for research etc, would be great to be able to tie it all together, will be watching with interest.
Cheers Tom.
 
OK - so the first step in the process is to create a base map - in pdf format, that will ultimately convert to a tiff image to be georeferenced.

For those wanting to use Geovic as the source of the actual pdf map, make sure you have a user account set up (not just utilising the software as an anonymous user) that way you can access the "vicmap_Topo - Jun 2014 (2m)" map under the topography and aerial imagery layer. I find this topo map to be the best base map, with most tracks etc being accurate.

For those not using geovic, the key thing is that the pdf map you produce from another source is accurate (spatially accurate, with consistent scale etc) and ideally with a grid placed over it. Most grids are fine (AMG, lat long, GDA) , as long as they can be converted to lats and longs in decimal format later. For this example I use GDA94 when I export from Geovic, because I then have another website program that allows me to convert the coordinate in to decimal format easily. If the program you use to create the pdf map has the ability to put grids in decimal lat/long format already then you would be able to skip a step. Geovic doesn't as far as I am aware.

For those that don't have a grid available - say its an image scanned from an old map or the website you are using to create the base map doesn't allow you to export the image with a grid on it, the best option would be to make sure there are distinguishable landmarks (at least 3 or 4) that you can then go in to google earth or similar and pick up the coordinate of the landmark with the cross hairs for georeferencing later.

For geovic users, create your map with the attributes you want (like the topo layer I mentioned earlier, historical mining activity etc, geology, deep leads) and then hit the print button and choose A4 or A3 landscape/portrait and choose the following output options:

1443148698_capture.png


Once you have exported and created a pdf map of your liking its time to start the tricky bit.

First thing that needs to happen is you convert the pdf to a tiff image. I use Adobe typically to do this, but not all adobe software has this capability (and I think the one I use on the work PC is an expensive copy), so maybe download the gimp software that Westaus refers to earlier in this thread.

Go through the motions of converting the pdf to the tiff image with your preferred file conversion software and try to keep the resolution at a good quality - the ones I do typically end up at about 1MB in file size. If you drop the quality the final map becomes a bit grainy.

Next step is to download and install the Q Landkarte GT software from source forge that I mentioned earlier in another post. This software is whats used to georeference the tiff image. I will save the explanation of how to do that in the next thread. Its complicated and cumbersome and took me a few attempts to nut it out, but once you crack it and make a few georeferenced tiffs its becomes more simple.

cheers,

Fever.
 
how to create the geo tiff - that's the map file that will eventually be loaded to the Avenza pdf maps app:

1) open Q landkarte GT software
2) Go to Map menu; select Edit / Create Map.
3) Select Convert a TIFF to GeoTIFF by geo referencing it.
4) Pick the correct projection.

Step 1
open the tiff image you created earlier (details in previous post) by clicking on the folder button of "input file" - its on the right hand side of the pic below:

1443173278_file.png


the output file will automatically be created in the same folder location with _tiff at the end, but you can change the name and location if you desire.


Map projection

Basically how the non-flat surface of the Earth is projected onto the flat surface of the map. As mentioned in previous thread I use GDA94 as the output from geovic - many others are available depending on where you are (GDA 94 works for the central vic goldfield) and no doubt this will be the point of frustration for anyone who tries this for themselves - it took me about 10 attempts to get it all to work, but haven't had an issue since.

1443172649_grid.png


Mode
The method of matching coordinates to the map. I always use linear as per pic:

1443172823_linear.png


this means you need to pick at least 3 points on the map and add their coordinates (steps which come later). I typically add 4 because the accuracy is better of the final map. I don't know about the other options here, stick with linear as its proven to work!

Step 2

Set the reference projection again for the output picture - basically repeat step 1 map projection bit I explained above in the step 2 window.

1443173885_step_2.png


final steps in another post later on..

fever.
 
I use V3, initially as an anonymous user until i realised there was more functionality as a (free) registered user, like the topo map mentioned earlier.

Cheers,
Fever
 
I apologise in advance for this because the next steps can be very frustrating, and only once you get a handle on all the little things that can go wrong will you be able to get this to work repeatedly. I just created three maps for avoca, ampitheatre and beaufort, with a couple of hiccups, but working now after a couple of attempts.

OK so part 2 of step two is to create reference points on the map that you have imported.

hit the "add ref button" 3 or 4 times depending on how many points you want to reference, I usually do 4 for better accuracy, but 3 is the minimum.

1443332775_add_ref.png


Now you have to move the little flags in the map image to the spots that you have known coordinates for.

Because my map has a grid on it that I created earlier in geovic I put my four points on the grid points close to each of the four corners of the image. Having the points further apart from each other improves the accuracy of the output image. Start with Ref 1 close to the bottom left, Ref 2 in top left, Ref 3 in top right and ref 4 in bottom right. If you don't have a grid on your image, find a landmark (like intersection of roads or something) and use google earth to find the coordinates of that point.

1443333013_shift_ref_to_known_point.png


once you have the coordiantes of each of your points you need to convert them to digital lats and longs to be able to enter them to this program. I just found a website that does this - www.fcc.gov/encyclopedia/degrees-minutes-seconds-tofrom-decimal-degrees

1443333231_convert_lat_long_to_decimal.png


with cords in decimal you then enter them in the ref areas - you need to separate the lat from the long with a space - and remember we are in southern hemisphere so the latitude needs to have a minus in front of it for south. I create a map once and it ended up in Greenland somewhere.

enter the decimal cords :

1443333354_finished_coords.png


you will notice that a grid x and y reference automatically appears beside the lats and longs - this is a good time to check that your points are in alignment as the grid refs should be the same for the same coordinates.

next step is to hit start process:

1443333480_start_process.png


the program will compute, and if no errors it will say "finished" at the end of a string of computations, and then a file will have been created in the directory you chose earlier.
1443333555_finished.png


before you close the program or attempt to create another map its a good idea to go and open the new georeferenced tiff image and make sure its not skewed. If it turns in to a pancake, or is wonky its because you have entered the wrong coords or grid reference. Start from the beginning!

if it looks normal you can then use in the PDF maps app. Check the instructions for loading images to that app. I use a dropbox account to store the images and then upload them in my phone.

I think a good practice start for this if you want to have a go is create a map of your house/street/suburb where you are actually sitting attempting this, because then once you have created the map in geovic or similar, georeferenced it and opened it in Pdf maps on your phone you should be able to see your location as sitting in your house and then you've nailed it!

best of luck, ask any questions.

fever.
 
Hey thanks Fever this works a treat. I followed your instructions to the letter and have not had a single problem.
Can't wait to put it to the test on the ipad this weekend.
 
Great wooly good to hear. I used my Beaufort maps this week and they were spot on. Spent considerable time digging a hole to about a foot n half for a chunk of lead.?

Least i know the detector works for non ferrous targets!
 
Hi,
I am the manager of the GeoVic system.
If you have any constructive suggestions for improvement , please let me know.
We are in the process of adding 5 deep lead maps into the system as background maps.
Also, are you aware that GeoVic has been set up to work on an Ipad (with reduced functionality)

regards

Rob
 

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