Cartographic modeling … a set of interacting, ordered map operations that act on raw data, as well as derived and intermediate map data, to simulate a spatial decision-making process (DeMers, 1997, p. 353) developed by Dana Tomlin (1990)

Cartographic modeling A cartographic model is a plan of how to proceed through an analysis, including the necessary data, operations on those data, intermediate results of those operations, and the final results of the analysis. A cartographic model is usually expressed in a flowchart of some kind.

Cartographic modeling No matter how much experience you have, flowcharting aids the modeling process by: diminishing the overall complexity of the task allowing the analysis to be planned out in an organized manner providing documentation

Cartographic modeling Steps in cartographic modeling for a site suitability analysis: 1. Identify the goal of the analysis 2. Identify the criteria for site suitability 3. Identify necessary data layers and GIS operations 4. Create a formal representation (e.g. flowchart) of how analysis should proceed 5. Go through analysis 6. Iterative refinement of analysis 7. Model verification Operation-alizing

Cartographic modeling Goal Rank land according to suitability for farming Criteria must be on fair or good soil must be on slope < 11 % must be > 10 meters from water Soil criteria is twice as important as slope Desire a ranking of land, if possible

Data Inputs Soils (vector) Elevation (raster) Waterbodies (vector)

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x add calcslope reclassify Elevation Slope SlopeRank SoilSlope BadSlope multiply Rough multiply Exclusive reclassify buffer rasterize Water WaterBuf WBufR Final

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x Soil RasSoil SoilRank 1 1 2 4 3 5 3 2 1 2 3 1 5 4 ID Type 1 xxxx 2 xxxx 3 xxxx 4 xxxx 5 xxxx rasterize reclassify ID Type 1 poor 2 fair 3 good 1 good 2 fair 3 poor 4 poor 5 good

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRankR2x SRank2x SoilRank 3 2 1 6 4 2 multiply x 2 ID Type 1 poor 2 fair 3 good ID Type 2 poor 4 fair 6 good

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x add calcslope reclassify Elevation Slope SlopeRank SoilSlope BadSlope multiply Rough multiply Exclusive reclassify buffer rasterize Water WaterBuf WBufR Final

Cartographic modeling calcslope reclassify Elevation Slope SlopeRank Elevation Slope SlopeRank 75 70 69 63 84 74 73 67 78 71 68 79 96 83 64 76 85 81 62 14 3 4 8 13 9 11 7 16 6 15 10 3 2 1 calcslope (not correct!) reclassify ID Slope 0 impossible 1 poor 2 fair 3 good 0 - 3 = 3 4 - 7 = 2 8 - 10 = 1 > 10 = 0

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x add calcslope reclassify Elevation Slope SlopeRank SoilSlope BadSlope multiply Rough multiply Exclusive reclassify buffer rasterize Water WaterBuf WBufR Final

Cartographic modeling SRank2x SlopeRank SoilSlope 6 4 2 3 2 1 6 7 4 3 5 9 8 2 add = ID Type 2 poor 4 fair 6 good ID Slope 0 impossible 1 fair 2 good

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x add calcslope reclassify Elevation Slope SlopeRank SoilSlope BadSlope multiply Rough multiply Exclusive reclassify buffer rasterize Water WaterBuf WBufR Final

Cartographic modeling Slope BadSlope 14 3 4 8 13 9 11 7 16 6 15 10 1 reclassify > 11 = 0 0 - 10 = 1 ID Status 0 excluded 1 included

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x add calcslope reclassify Elevation Slope SlopeRank SoilSlope BadSlope multiply Rough multiply Exclusive reclassify buffer rasterize Water WaterBuf WBufR Final

Cartographic modeling buffer rasterize Water WaterBuf WBufR Water WaterBuf WbufR B 1 B A B Buffer 10 meters rasterize ID Buffer A in B out ID Status 0 excluded 1 included A = excluded B = included

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x add calcslope reclassify Elevation Slope SlopeRank SoilSlope BadSlope multiply Rough multiply Exclusive reclassify buffer rasterize Water WaterBuf WBufR Final

Cartographic modeling BadSlope WBufR Exclusive 1 1 1 = x multiply ID Status 0 excluded 1 included ID Status 0 excluded 1 included ID Status 0 excluded 1 included

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x add calcslope reclassify Elevation Slope SlopeRank SoilSlope BadSlope multiply Rough multiply Exclusive reclassify buffer rasterize Water WaterBuf WBufR Final

Cartographic modeling Exclusive SoilSlope Rough 1 6 7 4 3 5 9 8 2 7 6 4 3 5 9 8 = x multiply ID Status 0 excluded 1 included

Cartographic modeling Rough Final 2 3 4 1 7 6 4 3 5 9 8 reclassify 0 = 0 1-3 = 4 4-5 = 3 6-7 = 2 8-9 = 1 ID Rank 0 Excluded 1 Best 2 Good 3 Fair 4 Poor

Cartographic modeling rasterize reclassify multiply Soil RasSoil SoilRank SRank2x add calcslope reclassify Elevation Slope SlopeRank SoilSlope BadSlope multiply Rough multiply Exclusive reclassify buffer rasterize Water WaterBuf WBufR Final

Cartographic modeling Can get large and complex diagrams Manage intermediate data layers Maintain documentation Model verification Question integrity of model - do the data and operations capture the real world process you are attempting to model? Does the model output suit the decision making needs of the organization? Check for logical inconsistencies (maps are helpful for this)

Cartographic modeling check for logical inconsistencies (maps are helpful for this) Slope Final 14 3 4 8 13 9 11 7 16 6 15 10 2 3 4 1 ID Rank 0 Excluded 1 Best 2 Good 3 Fair 4 Poor

Cartographic modeling Remember that GIS is for decision support, it is not the decision maker!