MapCalc Cross-Reference of Analysis Operations for
GRID/Spatial Analyst and ERDAS Imagine
Organization of MapCalc Analysis Operations
All GIS software contains procedures to encode, store, control, analyze and output maps. Five
fundamental classes organize the map analysis operations in MapCalc to include—
•
Reclassifying maps—operations CLUMP, CONFIGURE, RENUMBER, SIZE, and SLICE
•
Overlaying maps—operations COMPOSITE, COMPUTE, CALCULATE, COVER,
CROSSTAB and INTERSECT
•
Measuring distance and connectivity—operations DRAIN, RADIATE, SPAN, SPREAD
and STREAM
•
Characterizing neighborhoods—operations INTERPOLATE, ORIENT, PROFILE, SCAN
and SLOPE
•
Statistical relationships—operations ANALYZE, CLUSTER, COMPARE, CORRELATE,
REGRESS and RELATE.
This organizational scheme is based on the user's perspective of map input and output
contents—what the map(s) look like going in, and coming out.
RECLASSIFYING operations assign new values to each map category on an existing map layer.
Regardless whether you RENUMBER, SLICE, SIZE, CLUMP or CONFIGURE, the resulting map
will have the same "boundaries" (spatial arrangement) as the input map. The new values might
be ones you directly assigned (RENUMBER), or the ones the computer automatically assigns
(SLICE), or ones based on the area of each category (SIZE), or ones indicating the shape of the
individual features (CONFIGURE). If the same value is assigned to two adjacent categories, the
boundary disappears. In CLUMP, if a feature is composed of several discrete groupings, each
will each get a different value and the individual boundaries will be distinct. However, in all
RECLASSIFYING operations, the similarities in the spatial arrangement of features on the input
and output maps are readily apparent—just a different set numbers.
OVERLAYING operations are radically different as they assign new values based on the
independent values on two or more maps. Commands COMPUTE/CALCULATE (with map
variables), COVER and INTERSECT overlay maps on a "point-by-point" (cell-by-cell) basis. In
each instance, an entirely different looking map is generated as output. "Region-wide" overlay,
on the other hand, results in a map with similar spatial arrangement of features as those on the
"template" map. The map categories on the template map identify the locations (cells) whose
values from the "data map" are summarized. For example, the command “COMPOSITE
Districts_map With Slope_map Average For Avg_Slope” creates a map of the average slope for
each district. The result is a map with the same spatial arrangement of features—just new
values. The effect is similar to a RECLASSIFY, but two input maps are required.
DISTANCE MEASUREMENT operations assign values as a function of simple or weighted
connections among locations. In each instance, a map of "starter" locations is converted into a
map characterizing their connectivity to their surroundings. The connections can be "simple," or
"weighted" by intervening conditions. The SPREAD (proximity), and SPAN (narrowness)
commands identify the inter- and intra-distance of features. The RADIATE command identifies if
locations can be seen from the starter locations. The STREAM and DRAIN commands identify
the actual path(s) of the connections from starter locations.
NEIGHBORHOOD operations assign values that summarize conditions within the vicinity of map
locations (i.e., "roving window"). In the case of SLOPE, ORIENT and PROFILE commands, the
summary implies a characteristic of a surface, or gradient map. In the case of INTERPOLATE or
SCAN, the summary is a mathematical or statistical summary of the values within the
neighborhood.
STATISTICAL operations assign values as a function of the statistical relationships among maps.
In the case of ANALYZE descriptive statistics are reported for a stack of map layers. In the case
of CORRELATE and REGRESS the spatial relationship among maps is reported in tabular and
equation form. CLUSTER and RELATE generate a new map that shows the similarity among and
within maps, respectively. COMPARE produces maps and tabular comparisons between maps.
(return to top)
Cross-Reference to GRID/SA Operations (by ESRI)
GRID is a raster geo-processing toolbox that was integrated with the ARC/INFO vector GIS
system in the late 1980s. Spatial Analyst is a derivative of GRID and is distributed as an
extension to the ArcView and ArcGIS systems. The following listing is a cross-reference of
MapCalc and GRID/SA operations organized by the five analytical classes described above. The
analytical operations in GRID are grouped into 24 functional classes that are indicated in the body
of the listing (e.g., Shape Analysis function, Hydrologic function, etc.). Encoding, storage, control
and output operations are excluded from this cross-reference.
RECLASSIFY OPERATIONS: New values are assigned as a function of the initial value, size,
shape, or contiguity of each map category on a map.
•
CLUMP -- MapCalc operation that assigns new values to contiguous groups of cells within
each map category. Related GRID commands are
Shape Analysis function REGIONGROUP
Hydrologic functions STREAMLINK,STREAMORDER
•
COMPUTE (one map) -- MapCalc operation that assigns new values to each map location
as the mathematical or statistical function of the existing value. Related GRID commands
are
Arithmetic operator UNARYBoolean operator ^
Bitwise operators ,^^
Assignment operator =
Trigometric operators ACOS, ACOSH, ASIN, ASINH, ATAN, ATAN2, ATANH, COS,
COSH, SIN, SINH, TAN, TANH
Expodential and Logarithmic operators EXP, EXP10,EXP2, LN, LOG10, LOG2, POW,
SQR, SQRT
Selection functions SELECT, TEST
Statistical functions EQUALTO, GREATERTHAN, LESSTHAN, LPOS, UPOS
Other functions ABS, CEIL, CON, FLOAT, FLOOR, INT, INSUL, MERGE, PICK,
NORMAL, RAND, SCALAR, SETNULL
•
CONFIGURE -- MapCalc operation that assigns new values characterizing the shape of the
area associated with each category. Related GRID commands are
None, but shape statistics can be derived from ARC/INFO tables through user defined
scripts
•
RENUMBER -- MapCalc operation that assigns new values to the categories on a map.
Related GRID commands are
Reclassification function RECLASS
•
SIZE -- MapCalc operation that assigns new values according to the size of the area
associated with each map category. Related GRID commands are
Zonal functions ZONALAREA,ZONALPERIMETER,ZONALTHICKNESS
•
SLICE -- MapCalc operation that assigns new values by dividing the range of values on a
map into specified intervals (contouring). Related GRID commands are
Reclassification function SLICE
OVERLAY OPERATIONS: New values are assigned as a function of the independent values
associated with each map location or categories on two or more existing maps.
•
COMPOSITE -- MapCalc operation that creates a map summarizing values from one map
that coincide with the categories of another. Related GRID commands are
Zonal functions ZONALFILL, ZONALMAX, ZONALMEAN, ZONALMIN, ZONALRANGE,
ZONALSTD, ZONALSUM, ZONALVARIETY
•
COMPUTE (two or more maps) -- MapCalc operation that creates a map as the
mathematical or statistical function of two or more maps. Related GRID commands are
Arithmetic operators *, +, -, DIV, MOD
Boolean operators !, &, |
Relational operators =, ^=
Bitwise operators !!, &&, ||
Combinatorial operators CAND, COR, CXOR
Logical operators DIFF, IN, OVER
Statistical functions MAJORITY, MAX, MED, MIN, MINORITY, RANK, REGRESSION,
VARIETY
Other function FMOD
•
COVER -- MapCalc operation that creates a new map where non-zero values of the top
map replace the values on the previous (bottom) map, or stack of maps. Related GRID
commands are
Selection functions SELECTBOX, SELECTCIRCLE, SELECTMASK, SELECTPOINT,
SELECTPOLYGON
•
INTERSECT -- MapCalc operation that creates a map by assigning new values to pair wise
combinations of the values on two maps. Related GRID commands are
Combinatorial function COMBINE
DISTANCE OPERATIONS: New values are assigned as a function of the simple or effective
distance, optimal movement, narrowness, or visual connectivity among map locations.
•
DRAIN -- MapCalc operation that creates a map indicating the number of steepest paths
(optimal path density) from a set of locations along a surface. Related GRID commands are
Hydrologic function FLOWACCUMULATION
•
RADIATE -- MapCalc operation that creates a map indicating areas that are visible from
specified locations. Related GRID commands are
Visibility tools VISENCODE, VISIBILITY
•
SPAN -- MapCalc operation that creates a map indicating the narrowness within areas
associated with each category of a map. Related GRID commands are
None
•
SPREAD -- MapCalc operation that creates a map indicating the shortest effective distance
from specified cells to all other locations. Related GRID commands are
Distance functions CORRIDOR (compute sum), COSTALLOCATION (slice),
COSTDISTANCE, EUCALLOCATION, EUDIRECTION (orient), EUCDISTANCE
Shape Analysis functions EXPAND, SHRINK
Hydrologic function WATERSHED, BASIN
•
STREAM -- MapCalc operation that creates a map identifying the steepest downhill route
along a surface (optimal path). Related GRID commands are
Distance functions COSTBACKLINK, COSTPATH, PATHDISTANCE
Hydrologic function FLOWDIRECTION (orient)
NEIGHBORHOOD OPERATIONS: New values are assigned as a function of the independent
values within a specified distance and direction around each map location.
•
INTERPOLATE -- MapCalc operation that creates a continuous surface from point data.
Related GRID commands are
Surface functions IDW, KRIGING, SPLINE, TREND
•
ORIENT -- MapCalc operation that creates a map indicating aspect along a continuous
surface. Related GRID commands are
Surface function ASPECT
Distance function EUCDIRECTION
•
PROFILE -- MapCalc operation that creates a map indicating the cross-sectional profile
along a continuous surface. Related GRID commands are
Surface functions SAI, SHADE
•
SCAN -- MapCalc operation that creates a map summarizing the values that occur within
the vicinity of each cell. Related GRID commands are
Conditional statement IF, WHILE, DOCELL summaries within a DOCELL block using
Accumulative operators *=, +=, -=, /=, {=, }= and/or Assignment operator :=
Statistical operation POPULARITY
Focal functions FOCALFLOW, FOCALMAX, FOCALMEAN, FOCALMIN, FOCALRANGE,
FOCALSTD, FOCALSUM, FOCALVARIETY
Data Clean-up functions BOUNDARYCLEAN, MAJORITYFILTER, NIBBLE, THIN
Hydrologic functions FILL, SINK
•
SLOPE -- MapCalc operation that creates a map indicating the slope (1st derivative) along a
continuous surface. Related GRID commands are
Surface function SLOPE
STATISTICAL OPERATIONS: New values and statistical summaries are assigned as a function
of the numerical relationships among maps.
•
ANALYZE -- MapCalc operation that creates a map of the simple or weighted average,
standard deviation, coefficient of variation and several other descriptive statistics for two or
more maps (map stack). Related GRID commands are
STACKSTATS
MEAN (simple average only), MIN, MAX, MED, VARIETY, MAJORITY, MINORITY,
RANGE
•
CLUSTER -- MapCalc operation that creates a map that identifies areas with similar data
patterns (characteristics) using a stack of input map layers. Related GRID commands are
ISOCLUSTER
MLCLASSIFY (maximum-likelihood classification)
•
COMPARE -- MapCalc operation that generates a summary table of various comparison
statistics between two maps. Related GRID commands are
DIFF (determines which values are logically different)
Comparative statistics can be derived by evaluating index equations using GRIDMATH
•
CORRELATE -- MapCalc operation that generates a correlation matrix from a stack of
maps. Related GRID commands are
CORRELATION for a single pair of map layers
•
REGRESS -- MapCalc operation performs a linear regression analysis by using the "least
squares" method to fit a line through a set of data points in multiple maps (map stack) and
outputs the regression coefficients of the prediction model. Related GRID commands are
REGRESSION (Linear | Logistic)
•
RELATE -- MapCalc operation that creates a map that quantifies the similarity of each
location on a map to an evaluation data pattern, or set of comparison values. Related GRID
commands are
None
(return to top)
Cross-Reference to ERDAS Imagine Operations (by ERDAS/Leica)
Imagine is a powerful image mapping and visualization package with a robust set of grid-based
map analysis tools. Its historical roots are in remote sensing and image processing and has
particularly well-developed statistical operations.
RECLASSIFY OPERATIONS: New values are assigned as a function of the initial value, size,
shape, or contiguity of each map category on a map.
•
CLUMP -- MapCalc operation that assigns new values to contiguous groups of cells within
each map category. Related ERDAS commands are
CLUMP
SIEVE- deletes clumps smaller than user specified
ELIMINATE- similar to Sieve but dissolves smaller clumps into neighbors.
•
COMPUTE (one map) -- MapCalc operation that assigns new values to each map location
as the mathematical or statistical function of the existing value. Related ERDAS commands
are
RECODE
Trigometric operators: ACOS, ASIN, ATAN, COS, SIN, TAN
Expodential and Logarithmic operators: LOG, LN, SQRT
Other functions: Row, pi, modabs, int, even, odd, max, min, convert units, format
string/number, lowercase, uppercase
SINGLE INPUT ‘FUNCTIONS’
Trigometric operators: ACOS, ACOSH, ASIN, ASINH, ATAN, COS, COSH, SIN,
SINC, SINH, TAN, TANH
Expodential and Logarithmic operators: EXP, LOG, LOG10, SQRT
Other functions: ABS, ANGLE, BINARY, CEIL, CONJ, DELTA, EVEN, GAMMA,
IMAG, INV, ODD, REAL, RECT, ROUND, SIGN, STEP, TRI, TRUNC, WHOLE
•
CONFIGURE -- MapCalc operation that assigns new values characterizing the shape of the
area associated with each category. Related ERDAS commands are
PERIMETER
•
RENUMBER -- MapCalc operation that assigns new values to the categories on a map.
Related ERDAS commands are
RECODE
Trigometric operators: ACOS, ASIN, ATAN, COS, SIN, TAN
Expodential and Logarithmic operators: LOG, LN, SQRT
Other functions: Row, pi, modabs, int, even, odd, max, min, convert units, format
string/number, lowercase, uppercase
SINGLE INPUT ‘FUNCTIONS’
Trigometric operators: ACOS, ACOSH, ASIN, ASINH, ATAN, COS, COSH, SIN,
SINC, SINH, TAN, TANH
Expodential and Logarithmic operators: EXP, LOG, LOG10, SQRT
Other functions: ABS, ANGLE, BINARY, CEIL, CONJ, DELTA, EVEN, GAMMA, IMAG,
INV, ODD, REAL, RECT, ROUND, SIGN, STEP, TRI, TRUNC, WHOLE
•
SIZE -- MapCalc operation that assigns new values according to the size of the area
associated with each map category. Related ERDAS commands are
Size of each value is always present in ‘Histogram’ column of every image (mandatory)
CLUMP (reports clump pixel size)
•
SLICE -- MapCalc operation that assigns new values by dividing the range of values on a
map into specified intervals (contouring). Related ERDAS commands are
TOPOGRAPHIC LEVEL SLICE (refers to DEM, but any raster is fine)
OVERLAY OPERATIONS: New values are assigned as a function of the independent values
associated with each map location or categories on two or more existing maps.
•
COMPOSITE -- MapCalc operation that creates a map summarizing values from one map
that coincide with the categories of another. Related ERDAS commands are
ZONAL ATTRIBUTES (Raster summary of Vector regions, must have template in Vector)
•
COMPUTE (two or more maps) -- MapCalc operation that creates a map as the
mathematical or statistical function of two or more maps. Related ERDAS commands are
TWO INPUT ‘OPERATORS’
Add, subtract, Multiplication, Division, Power and MOD
INDEX
•
COVER -- MapCalc operation that creates a new map where non-zero values of the top
map replace the values on the previous (bottom) map, or stack of maps. Related ERDAS
commands are
OVERLAY (you specify if min or max value of each cell in the two layers takes priority)
Combined with Recode command allows same functionality with several steps
i.e. masking data
•
INTERSECT -- MapCalc operation that creates a map by assigning new values to pair wise
combinations of the values on two maps. Related ERDAS commands are
MATRIX
DISTANCE OPERATIONS: New values are assigned as a function of the simple or effective
distance, optimal movement, narrowness, or visual connectivity among map locations.
•
DRAIN -- MapCalc operation that creates a map indicating the number of steepest paths
(optimal path density) from a set of locations along a surface. Related ERDAS commands
are
None
•
RADIATE -- MapCalc operation that creates a map indicating areas that are visible from
specified locations. Related ERDAS commands are
VIEWSHED ANALYSIS
•
SPAN -- MapCalc operation that creates a map indicating the narrowness within areas
associated with each category of a map. Related ERDAS commands are
None
•
SPREAD -- MapCalc operation that creates a map indicating the shortest effective distance
from specified cells to all other locations. Related ERDAS commands are
SEARCH (Euclidean distance only)
•
STREAM -- MapCalc operation that creates a map identifying the steepest downhill route
along a surface (optimal path). Related ERDAS commands are
None
NEIGHBORHOOD OPERATIONS: New values are assigned as a function of the of the
independent values within a specified distance and direction around each map location.
•
INTERPOLATE -- MapCalc operation that creates a continuous surface from point data.
Related ERDAS commands are
3-D Surfacing
•
ORIENT -- MapCalc operation that creates a map indicating aspect along a continuous
surface. Related ERDAS commands are
ASPECT
•
PROFILE -- MapCalc operation that creates a map indicating the cross-sectional profile
along a continuous surface. Related ERDAS commands are
None but might be possible using Spatial Modeler
•
SCAN -- MapCalc operation that creates a map summarizing the values that occur within
the vicinity of each cell. Related ERDAS commands are
NEIGHBORHOOD: Sum, Diversity, Density, Majority, Minority, Max, Min, Rank
•
SLOPE -- MapCalc operation that creates a map indicating the slope (1st derivative) along a
continuous surface. Related ERDAS commands are
SLOPE
STATISTICAL OPERATIONS: New values and statistical summaries are assigned as a function
of the numerical relationships among maps.
•
ANALYZE -- MapCalc operation that creates a map of the simple or weighted average,
standard deviation, coefficient of variation and other descriptive statistics for two or more
maps (map stack). Related ERDAS commands are
?
•
CLUSTER -- MapCalc operation that creates a map that identifies areas with similar data
patterns (characteristics) using a stack of input map layers. Related ERDAS commands are
?
•
COMPARE -- MapCalc operation that generates a summary table of various comparison
statistics between two maps. Related ERDAS commands are
?
•
CORRELATE -- MapCalc operation that generates a correlation matrix from a stack of
maps. Related ERDAS commands are
?
•
REGRESS -- MapCalc operation performs a linear regression analysis by using the "least
squares" method to fit a line through a set of data points in multiple maps (map stack) and
outputs the regression coefficients of the prediction model. Related ERDAS commands are
?
•
RELATE -- MapCalc operation that creates a map that quantifies the similarity of each
location on a map to an evaluation data pattern, or set of comparison values. Related
ERDAS commands are
None
(return to top)
