Clarification & Tips for EOTopo Map Users

Submitted: Wednesday, Jan 24, 2018 at 20:52
ThreadID: 136148 Views:827 Replies:2 FollowUps:4
We've received quite a lot of interest as you can imagine about the upcoming release of EOTopo 2018 maps and a number of points are coming up that I thought I'd clarify for those that are a little unclear, or would like to know.

MAP QUALITY & FORMAT
There are two core factors when reviewing a map for "quality".

The first is the scale. Scale refers to the size of detail offered in the map. For a scale where 1cm on the map equals 200,000 cm (= 2km) on the ground you have a 1:200,000 scale map, also referred to as 200K. So when we refer to the EOTopo raster map being 200K and 144K, the latter is more detailed because 1cm on the map represents 14.4km instead of 2km.
144K scale EOTopo maps have been offered since 2016, both online (EOTopo Online) and in the Premium ExplorOz Traveller app (offline Premium). But this will be the first time that we have released a RASTER product at the more detailed 144K scale. We will produce EOTopo 2018 Raster in OZF4 and ECW formats for download only.

The second issue is resolution. In computer graphics a raster image is a dot matrix of pixels of various colours, which together form an image. For us to produce maps out of our database for distribution we firstly have to extract raster images from our databases in GeoTIFF format. The format of an image has a direct bearing on its overall quality but there are only a few formats that can be used for raster map images that retain the geocoding information and the different mapping software programs in use today each have their own file format protocols. This is why we only offer the ECW and OZF4 formats. Please note that these versions of EOTopo maps are high quality resolution at 200dpi built using the full 256 colour palette.

EOTOPO MAP PRODUCTION
We can actually produce EOTopo 2018 data at Level 20 (1.1K scale maps) but have deliberately chosen 200K and 144K as the best scale for their application in the ExplorOz community as whole of Australia raster maps.
Because the source data is so detailed we actually have more data to put on the map files than can realistically fit on the 144K and 200K outputs without looking very cluttered. ie. not every track can be labelled with its name, not all features can be shown. So zoomed into an area at 18K on the online map you will see more detail and features than what can be shown in the 200K raster extraction and 144K will give more/different details than the 200K.

To make the determination of what detail "drops off" and what remains is a very complex set of system parameters/rules that are applied to each attribute in the database. The rule is fixed for that attribute/feature across the whole of Australia map, and sometimes how one particular attribute is handled affects other attribute features. Further more the look/feel of an attribute/feature has to be exactly the same across the entire map - whether that is in the city or the outback. As you can imagine, this results in certain compromises but as an Australia company with extensive first-hand knowledge of just about everywhere in Australia we can make good judgements about these parameters and believe we produce a high quality map with the best fit for the application of the map in the ExplorOz user base. ie. we give priority to some attributes over others.

THE DIFFERENCE BETWEEN EOTOPO MAPS
The first thing to really understand is that features on raster maps do not alter size/or become more detailed when you zoom in (they just become blurry), whereas the online map system and the map system in our app ExplorOz Traveller uses tiled raster zoom, where each zoom level is a specific raster sheet created at a specific scale so when zooming in you move between different scales so you will get more detail as you zoom in closer.

The 2nd thing to understand is that on the RASTER maps we cannot clutter up the map with all the feature types that we have in Places system but have chosen to display campsites, caravan parks, and other accommodation (symbols and labels) plus we show the Point of Interest place type (also shown with a symbol - camera). However, when viewing the EOTopo maps in the ExplorOz Traveller app, Places is a separate data layer so you can turn on/off all 8 categories of Places or filter just the ones you want to see - there are 90,000 Places in our database. This database is managed live on our server and app users have free access to refresh the Places data via the app anytime.
So there are really 3 methods to view/use EOTopo maps and they are different.

1. EOTopo raster map sets - offline
2. The Premium ExplorOz Traveller mapset - offline
3. EOTopo online

*There are also two additional methods of using the EOTopo online maps - you can go to Places on the website and press Map. This shows the map in a similar way to how you see it in the app, with all Places overlayed. You will see coloured numbered dots to indicate there is a cluster of Places - click to enlarge and separate the Place clusters. The number refers to how many Places. The other way to see the EOTopo map is in Treks (Trek Notes).
HOW TO GET YOUR EOTOPO 2018 UPGRADE
These are not yet available so you have to wait until February and we will let you know via newsletter, forum, and facebook.

But there is one thing you can do - if you already own EOTopo 200K and purchased this from ExplorOz (not Memory-Map) are planning to get the EOTopo 2018 Raster update (for use in OziExplorer, Hema Navigator, Track Ranger) then you must check that you can login to ExplorOz because you will not be able to access the upgrade pricing if you cannot log in to the ExplorOz website and access your account profile where you past shop orders and invoice history is stored. The system must be able to validate your past purchase of EOTopo200K through your registered ExplorOz account profile. If you have any troubles I am here to help. Call or use Live Chat to reach me.

PRICE
Existing owners of EOTopo200K raster mapsets will have a choice to upgrade to either the 200K product or the 144K product at either $20 or $40 respectively.
Both the 200K product and the 144K product will be avail for sale to new users - the 200K will be called Standard, and the 144K will be called Premium. Price will be $79.95 and $99.95 respectively, unless you are an ExplorOz Member in which case you get a 5% discount.

** PLEASE SHARE WITH EVERYONE WHO YOU THINK IS INTERESTED IN NEW MAPS **
Please feel welcome to contact me for advice, or help or clarification. Live Chat is great, or email, or call me. Please note I do work part-time but I will respond promptly.
Michelle Martin
Customer Support - ExplorOz & ExplorOz Traveller

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Reply By: Member - Boobook - Thursday, Jan 25, 2018 at 07:20

Thursday, Jan 25, 2018 at 07:20
Thanks Michelle.

Is it possible to show examples of 200K, 144K and the new high sale map (25k?)

I have looked and cant see a lot of difference. As to the scale I know that 144k implies closer view than 200K but the scale thing is meaningless on a computer / phone. It would be useful to easily see the difference to determine the value.


A 200K map on a 30" monitor on a home PC is in reality a different scale to that same map at the same zoom level on a phone, and neither are 200K nI am not sure why every map manufacturer uses a scale unless it is for a paper map.

I would love to trial the products. I have asked for it before. I hope you can find a way to do a time limited trial. Memory Map do that for 3 or 7 days, and nearly every time I buy the products. Pleeeeeze
Tony
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Follow Up By: ExplorOz Team - Michelle - Thursday, Jan 25, 2018 at 11:54

Thursday, Jan 25, 2018 at 11:54
Correct screen resolution plays a part but more importantly the viewing program you use. I wanted to touch on this subject but it gets complicated - maybe David will chip in and explain...

Some numbers for you: If viewing the 144K raster map on a computer screen our 200dpi map is actually being rendered at a resolution of approx 83K. The 200K is about 96K. But this depends on the resolution output of the program you are using. The detail on the map doesn't change because it is raster - but the size of how much space the image fills on your screen is dependent on the device/program configuration.

David can tell us the spatial resolution for the 200K map in the 200dpi image, the target pixel size (using degrees) is 0.000228584281539. For the 144K it is that number x 0.72 (=0.0016458068270808).

I can do some screen shots at a later stage once we've produced the raster images but of course you can use the zoom controls in the EOTopo Online map to see the variance in detail as this is showing the raster tiles (although a new version is yet to be published prior to final release as we have already made some modifications). Level 12 is 288K. Level 13 is 144K.

Free trials of the app are not practical. We're not going down that path sorry. You can see enough of the map to get a gauge of if you like it or not and there is lots of available reading to help you decide if the features of the app are for you or not. I am also told that the app stores have a 24 hour cancellation refund policy. Not sure how that works but you can look into it.
Michelle Martin
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Follow Up By: ExplorOz Team - Michelle - Thursday, Jan 25, 2018 at 16:59

Thursday, Jan 25, 2018 at 16:59
So, in an attempt to simplify all this - the resolution of the map created at 200dpi tell us the detail in terms of clarity of the actual image file - ie. based on the number of pixels per unit in the raster image. How a screen then renders these pixels (bigger, smaller) to fit them across the screen is based on the screen resolution of the device (and how the program renders the image, and whether it is a retina display etc).

So on some devices the same image file will appear larger than when viewed on other devices - not just because of the screen size, but the resolution setting of the screen and map viewing program. But here we go back to the root of the raster issue - just because an image can be viewed at a larger physical dimension does not give more map detail this is because the maps are RASTER images and you will not get more detail by enlarging the raster image.
Michelle Martin
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Follow Up By: Member - Boobook - Friday, Jan 26, 2018 at 18:48

Friday, Jan 26, 2018 at 18:48
Well I am glad you cleared that up Michelle.

???
Tony
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Reply By: Geoff N (NSW) - Wednesday, Feb 21, 2018 at 21:22

Wednesday, Feb 21, 2018 at 21:22
G'day.
Don't know where's best to post this but there is no 144K Australia in my OZF download list whereas there is one in the ECW download list.
Shall put this in the Forum as well.
Cheers!
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Follow Up By: ExplorOz Team - Michelle - Thursday, Feb 22, 2018 at 12:52

Thursday, Feb 22, 2018 at 12:52
HI Geoff,
I've already replied to your Member Message but that is correct. There is no single Australia file in OZF in the 144K scale, only in the ECW format.

It was a production issue - the img2ozf software to process the 144K sheet just couldn't handle the file size. We have been in contact with Des Newman but there is not much we can do. The 144K ECW will work in most devices and if you want a single sheet I would recommend you give this a go. Alternatively, if you must use OZF then download each of the 6 state files to get the Australia-wide coverage.
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