Merge pull request opencv#10756 from terfendail:orb_firstlevel

Author: alalek

modules/features2d/include/opencv2/features2d.hpp

@@ -307,7 +307,7 @@ class CV_EXPORTS_W ORB : public Feature2D
     input_image_linear_size/pow(scaleFactor, nlevels - firstLevel).
     @param edgeThreshold This is size of the border where the features are not detected. It should
     roughly match the patchSize parameter.
-    @param firstLevel The level of pytramid to put source image to. Previous layers are filled
+    @param firstLevel The level of pyramid to put source image to. Previous layers are filled
     with upscaled source image.
     @param WTA_K The number of points that produce each element of the oriented BRIEF descriptor. The
     default value 2 means the BRIEF where we take a random point pair and compare their brightnesses,

modules/features2d/src/orb.cpp

@@ -673,7 +673,7 @@ class ORB_Impl : public ORB
     void setEdgeThreshold(int edgeThreshold_) { edgeThreshold = edgeThreshold_; }
     int getEdgeThreshold() const { return edgeThreshold; }
 
-    void setFirstLevel(int firstLevel_) { CV_Assert(firstLevel >= 0);  firstLevel = firstLevel_; }
+    void setFirstLevel(int firstLevel_) { CV_Assert(firstLevel_ >= 0);  firstLevel = firstLevel_; }
     int getFirstLevel() const { return firstLevel; }
 
     void setWTA_K(int wta_k_) { wta_k = wta_k_; }