Read the article "New heat maps in the REG procedure." At the end it describes how to control whether the procedure uses heat maps or scatter plots. To quote from the article:
"In SAS 12.1 the MAXPOINTS= option accepts two arguments, and the default values are MAXPOINTS=5000 150000. The first argument specifies the data size for which heat maps are used instead of scatter plots. The documentation of the MAXPOINTS= option states that "when the number of points exceeds [the first number] but does not exceed [the second number] divided by the number of independent variables, heat maps are displayed instead of scatter plots for the fit and residual plots." In other words, if you have a regression with k explanatory variables, heat maps are used when the number of observations is between 5,000 and 150,000/k. Of course, you can use the MAXPOINTS= option to change either or both of those values."
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