Avenza – Georeferencing PDF Maps for Use in Avenza PDF Maps

arcgis-desktopavenzageoreferencinggeospatial-pdfglobal-mapper

I have PDF maps like the one below (normally PDF, but JPEG for this) that I would like to be able to georeference to use with Avenza PDF maps.

I don't have GIS training, but have access to Arcmap 10.1 and Global Mapper (I looked at the Avenza software, but it is out of my price range).

How involved is Georeferencing the maps? I have the scale, projections and GPS points but am unsure of how to proceed.

Map M

Best Answer

Ok the less technical answer is as follow:

Your sample has a lat/lon grid which I am almost certain will be WGS84, grab 4 corners that have clearly lat/lon labelled and georeference considering those points and WGS84 data, you could add a few more points since its a grid to minimize distortions

By the way you should just download QGIS from www.qgis.org its open source and has georeference capabilities, Avenza PDF maps accepts geotiff also that you can upload to the store for approval (if you intend to sell/provide) or you can read directly from your device

P.S. you will need to convert from PDF to JPG probably

Related Solutions

[GIS] Is it possible to georeference an existing, un-georeferenced pdf

I know this question is old, but I had this issue recently and eventually came out with a way to do this.

This can be accomplished by using Osgeo's gdal, which happens to have a PDF driver included. Basically you can do something like:

from osgeo import gdal
#Open your Unreferenced PDF
src = gdal.Open("originalFile.pdf")

Then obtain or calculate somehow the desired Projection System and Geotransform you want to add to the PDF. For example, we can extract those from a GeoTiff by doing:

#Open the Tiff to obtain its data from
geoTiff = gdal.Open("someMap.tif")
#Obtain its Projection system and its Geotransform
coords = geoTiff.GetProjection()
gt = geoTiff.GetGeoTransform()

Finally, set the projection and geotransform to your PDF and then create a copy with the PDF Driver:

src.SetProjection(coords)
src.SetGeoTransform(gt)
#Instantiate a PDF driver and save your Referenced copy
pdf_driver = gdal.GetDriverByName("PDF")
dst = pdf_driver.CreateCopy("referencedFile.pdf", src, 1)

The result is a PDF that is georeferenced to have its upper-left corner placed at location gt using the Projection System coords. This can be verified by opening the PDF on QGis or ArcGis, or well by using the gdalinfo command on your referenced PDF.

Georeferencing Photos – How to Georeference with No Spatial Reference in ArcGIS Desktop

Knowing the position of the camera, relative to the ground, and assuming the ground to be flat, it should be possible to create target control points at each of the four corners of the image. Then pass those control points to the Warp tool. The source control points would be found by examining the unprojected extent of the image.

To use a higher order transformation, I think you'll need additional control points at interior points, thereby adjusting the scale of the image in the middle more than near the edges.

Warp is useful when the raster requires a systematic geometric correction that can be modeled with a polynomial.

Update

If you just want a quick and dirty approach, then you might be better off building a world file for each photo, by adding an offset to the mid point (assuming that's where your GPS point falls) to describe the corner of the photo, and a pixel size in the linear units of whatever projection you're using.

Best Answer

Related Solutions

[GIS] Is it possible to georeference an existing, un-georeferenced pdf

Georeferencing Photos – How to Georeference with No Spatial Reference in ArcGIS Desktop

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