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Stitching Images into Maps

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Workshop 4: Stitching Images Into Maps

Once you have collected your images, you should set aside a block of time (at least 2 hours) to sort them and stitch them into a map. It is best to do this as close to the time that you collected them as possible (within the next 3 days).

You can build your map using the Public Lab open source MapKnitter.org. There you will use the same login from your Public Lab account. To learn the basics of map stitching, this video offers a great introduction video:

Sorting your Images

It is easier to sort through your images first for ones that you can use on your map than to start from your entire set of images you collected mapping. There are many ways to sort your images.
- The easiest way is to go through all your images and cull out the best 30 or so that show a the geographically diverse areas of your site. (Recommended)
- Here are suggestions for windows or for macs and go through those for photos that you’d like to use for your site.
- Other people have used file size to help them sort images.
- You can choose not to sort and find a good photo to use as your base and build your map from there.

Once you have gone through your images, pick one that has a clear, distinguishable feature that you will be able to build your map off of. We call this your “base image,” and I suggest you rename it as such.

Note on Infragram images:

If you are using the infragram point and shoot images, your images will be distorted by a fish eye lens. They will need to be corrected before you can stitch them in Mapknitter. One way to do this is by using the opensource software GIMP. Here are some directions on how you can do this.

Starting your map:

Logging on to mapknitter there is a column on the right hand site where you can build a map. This will ask you to:
1) Name your map
2) Identify the location (address or coordinates)
3) Give a description (Suggested comments include: the date the images were captured, weather that day, who mapped the site and why you were interested in collecting the data.) This information can be edited later.

Uploading your images into Mapknitter:

1) Start with uploading your base image and upload it into Mapknitter.
2) Place your image over the map so it aligns as closely as it can with the base images. Helpful features in the toolbar include:
- Toggle (t)
- Distort (d)
- Rotate (r)
- Transparency
- Lock (l) (once your images are where they fit best)
3) Once your base image is set and locked, upload another image that shows a part of your site that abuts the base image. They should overlap slightly.
4) Repeat steps 2-4 until your map is complete and shows all of the site you were hoping to map.
5) Once your map is complete you can annotate it using the annotate toolbar.

Using your map:

Writing a research note is a great way to share your work. The tab on MapKnitter entitled “Post” will bring you to a page where you can write a research note on PublicLab.org. To embed your map in the note, go to the “About” tab on mapknitter, click the “embed code” button and copy/paste it in your research note. MapKnitter maps can also be shared via URL or embedded into blog posts or other web pages.

Exporting your map:

(optional) Sometimes you need to print a map out! Exporting your map allows you to download it in different formats, often for printing. You can download your map in many formats. (JPG, Geo-TIFF, Tiled Map Service, OSM-style etc.)

When you’re finished working on your map, click the export button. Exporting can take some time, if it takes longer than 2 hours, we suggest you check the advanced options tab and reduce the resolution of your map and try to export it again.

Let the community know what you’re mapping on the mailing lists!