Wednesday, July 27, 2011

Canadian Land Inventory Inaccuracies

The following is an excerpt of the answer we received when inquiring about why the Canadian Land Inventory seemed to be inaccurate...

Neither GIS nor high-resolution DEM's existed in the era of either soil or CLI initial map product development for Simcoe County. Today's digital products, available through the Land Information Ontario warehouse, are the products of attempts to "modernize" the original paper map products.
Unfortunately, the map digitizing pre-dated the DEM development and the rationalization of the soil and CLI polygons into their proper landscape positions was overlooked - until now.

The precision of landscape rendering - as performed by an Ontario Land Surveyor - far exceeds the current spatial resolution and accuracy of the soil maps and derivative products - like the CLI layer. The new Greater Toronto Area (GTA) DEM has sub-metre vertical accuracy. It is superior to the current provincial DEM. Neither of these DEM's approaches the accuracy of products that an Ontario Land Surveyor should produce for landscape location of boundaries and features. The problem is that the perception of scale and accuracy of the soil map products does not meet the reality of their application - except by people such as yourself who saw through this issue immediately. We have started down a road of renewal of the soil map resources of the Lake Simcoe watershed (and will then move to the extent of high-resolution DEM availability in the rest of the GTA DEM coverage). We are also acquiring LiDAR data clouds, creating LiDAR-derived high-resolution DEM's and moving to much more detailed predictive soil mapping in selected areas of the province. At present, however, we have not completed this work for the C.F.B. Borden area of Simcoe County.

An estimate of the margin of error associated with these current soil map (and derivative) products may be derived, somewhat at least, from the input data density requirement to create the original 1:63,360 map product.
However, we can find no metadata records of how rigorously this mapping protocol would have been applied on any individual acreage of the map area.
I am very sorry, but this remains a major weakness in the current Ontario soil map products across the province.

On behalf of OMAFRA and the current Soil Resource Information Team, thanks very much for your inquiry and interest in the Simcoe County soil and CLI map products. If you have a project in mind for adding value and precision to the soil mapping in the area, please contact me directly. We would be pleased to discuss options and opportunities for soil information data improvements with you.



Stewart J. Sweeney, Ph.D.
Environmental Management Branch,
Ontario Ministry of Agriculture, Food and Rural Affairs


  1. You have mentioned quality stuff about land surveyors. I just wanna suggest that it is important to survey the land before buying it otherwise problems may arise and could not be fixed later.

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