Getting started
From SnapMap
This Getting started page will show you how to create an account at SnapMap and move around the main map. It then explains how to add photos, and add tags to those photos, including location and date tags.
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Creating an account
- Go to http://www.snapmap.org/
- Get through the HTTP authorization using the login that should have been emailed to you.
- Click 'Sign in'.
- Create an account, and click the confirmation email when it arrives.
The SnapMap home screen
The home screen of SnapMap shows a map defaulting to London, with shortcuts to some other pre-defined places that have several photos. Scroll around and click the yellow markers to see how the user interface works. An arrow on a yellow marker represents the direction the photo was taken. Clicking once on a yellow marker brings up a little window showing a thumbnail of the photo. Click on this thumbnail to go to a photo page.
When you zoom or scroll around the map, the web page connects to the SnapMap server (using AJAX) and downloads any markers that are in the new area. It currently uses 60 as the maximum number of photo markers shown at once. If there are more than 60 photos, then a paging interface appears below the photo.
You may also notice some pale red markers on the map. These represent photos for which only an approximate location could be determined from the photo's tags. Yellow markers mean accurate locations.
SnapMap photo pages
Every photo added to SnapMap gets its own photo page. Its URL is of the form http://www.snapmap.org/<nnnn> where <nnnn> is an integer. This is its SnapMap photo id.
The photo page shows a medium size version of the image, along with a user interface that shows:
- a map centred on the photo, depicting:
- the photo location
- the direction the photo is pointing
- and the horizontal field of view if it has been defined.
- a list of all tags linked to the photo
- a UI for marking the photo a favourite
Adding a photo
Note: Photos themselves are not uploaded to SnapMap. Instead, one adds photo records that point to photos hosted elsewhere. Although most photos on the web can be added to SnapMap in this way, there are exceptions when images are loaded with JavaScript or Flash, or where the image is made up of multiple tiles.
Simple method, using a scraper
All images on Flickr and Wikipedia can be added to SnapMap. For each, a “scraper” script loads the given webpage, locates the actual image file, and adds certain tags to the photo. So these websites make a good choice to start with. Here’s how to add a photo from Flickr or Wikipedia:
- Find an image on Flickr or Wikipedia that you can locate on the map; copy the URL of the image page into the copy buffer.
- Click New in the Images section of the sidebar.
- Paste that URL into the Webpage input box, and click Add.
That’s it! SnapMap now redirects you automatically to the new photo page. It’s a good idea to check through these tags, to see what data has been imported by the scraper.
On the New image page, note how there are several other websites – FromOldBooks, Leodis, the National Gallery, and English Heritage Viewfinder – where adding images is made easy using a scraper. In principle, any website that displays images in a consistent manner can have a scraper written.
Feel free to add as many image records as you like from these sites.
Note that there’s an input field for new images on the SnapMap home screen, so you don’t need to go to the New image page.
Advanced method, without a scraper
Next we’ll try adding a photo from a website that doesn’t yet have a scraper written. (If there are just a few images on a particular site, it’s not worth writing a scraper.)
It’s mostly the same as the simple method, except the URL must be the webpage, not the URL direct to the image:
- Find an image on the web that you can locate on the map. Copy the URL of the page it is on into the copy buffer.
- Click New in the Images section of the sidebar.
- Paste that URL into the Webpage input box, and click Add.
- Use the image picker to choose the image you want. Click the left and right buttons on-screen, or click the table row. Use the width and height indicators to distinguish between full-size and thumbnail images. Click Add photo to create the image record.
At this point, we have a minimal image record. Its tags should contain a src (tag) and a webpage (tag), but little else. Scour the webpage it came from for any other basic information that you can add as tags, for example title (tag), description (tag) or date (tag).
Adding tags to a photo
Tags in SnapMap take the form of:
- <key> = <value>
- <key> is a text string, with length from 0 to 255 characters
- <value> is a text string with no maximum length
Unlike some tagging systems, a photo may have multiple tags using the same key, and the zero-length key is acceptable.
Although SnapMap users are free to use and invent whatever keys they like, many keys have special uses and will be treated in certain ways by SnapMap, particularly in respect of date and location.
Add tags by scrolling to the bottom of a photo page, entering your key and value strings in the first tag boxes, then clicking Add.
Note that you can add, edit and delete your own tags freely, but you cannot edit or delete tags that other people have added.
Using Wikipedia URLs as tags
You can use Wikipedia URLs as tags (key="", value=<wikipedia_url>) to tell images roughly where they are. Not only does this make a handy approximation for later, more accurate positioning, but it also helps to unify photos semantically better than free-form text tags.
For example, add "http://en.wikipedia.org/wiki/Euston_railway_station" as a tag (with an empty key) if the photo is taken in or around that station. Note the pale red dot that appears on the map.
- For more, see Wikipedia tags.
Date and time tags
Many photos on Flickr include timestamp data. This is imported by the Flickr scraper as, for example:
- datetime=2007-09-20 17:21:58
You can add your own tags like this if you know them. Often, only the approximate date is known, so you can add tags such as:
- datetime=2007-09-20 17:21
- date=2007-09-20
- date=2007-09
- date=2007
- For more, see Date and time tags.
Adding location and view data to a photo
It’s possible that a newly added photo will already have location data attached. (If so, the map on the photo page will reflect this. If not, it will just show the whole world.) The Flickr and Wikipedia scrapers, for example, know to check the source photo pages for coordinate data. However, since neither site records the accuracy of such data, it will be recorded as approximate in SnapMap (and hence get a pale red marker on the home screen map).
If a Wikipedia tag has been added (see above), again it is possible that an approximate location is now known.
Adding a slingshot view
Using the slingshot view tag is probably the easiest way to add location and orientation data to photo.
- For more, see slingshot view.
Any photo with a pale red icon is suitable for adding a slingshot view to. Pale red means SnapMap has been told only roughly where the photo is. After a slingshot view is added, it will get a directional yellow icon.
Adding a PhotoOverlay view
PhotoOverlay views are ideal for aerial photography. They make use of Google Earth, and its ability to set up views just like that of a given photo. It’s a little fiddly to match views manually, but with practice can typically be done in 3 minutes or so.
- For more, see PhotoOverlay view.
Rating photos
You can make any photo a favourite. When signed in, click the light grey star to the left of the image title to toggle fave/unfave.
As well as being listed in your favourites section, this data may be aggregated so as to choose certain photos over others when given a limited space. For example, on the home screen it might be useful to show favourites first, then others.
- For more, see Rating images.
Adding comments to a photo
Any photo can have comments added, as in Flickr. Comments are given a timestamp and attributed to a user. Feel free to comment about anything: that you love the photo, that its location data is wrong, that it’s inappropriate for public display, etc.
- For more, see Commenting on images.
Deleting photos
Don’t worry, for now, about creating bad photos and bad tags. Let Laurence know and they’ll be dealt with.
