diff --git a/src/StdPrs/StdPrs_WFDeflectionRestrictedFace.cxx b/src/StdPrs/StdPrs_WFDeflectionRestrictedFace.cxx
index b925fcd67c..da03c7de50 100755
--- a/src/StdPrs/StdPrs_WFDeflectionRestrictedFace.cxx
+++ b/src/StdPrs/StdPrs_WFDeflectionRestrictedFace.cxx
@@ -142,6 +142,7 @@ void StdPrs_WFDeflectionRestrictedFace::Add
   gp_Pnt dummypnt;
   Standard_Real ddefle= Max(UMax-UMin, VMax-VMin) * aDrawer->DeviationCoefficient();
   TColgp_SequenceOfPnt2d tabP;
+  Standard_Real aHatchingTol = 1.e100;
 
   UMin = VMin = 1.e100;
   UMax = VMax = -1.e100;
@@ -169,6 +170,7 @@ void StdPrs_WFDeflectionRestrictedFace::Add
 	      UMax = Max(P2.X(), UMax);
 	      VMin = Min(P2.Y(), VMin);
 	      VMax = Max(P2.Y(), VMax);
+              aHatchingTol = Min(P1.SquareDistance(P2), aHatchingTol);
 
 	      if(Orient == TopAbs_FORWARD ) {
 		//isobuild.Trim(P1,P2);
@@ -215,6 +217,8 @@ void StdPrs_WFDeflectionRestrictedFace::Add
 	UMax = Max(P2.X(), UMax);
 	VMin = Min(P2.Y(), VMin);
 	VMax = Max(P2.Y(), VMax);
+        aHatchingTol = Min(P1.SquareDistance(P2), aHatchingTol);
+
 	if(Orient == TopAbs_FORWARD ) {
 	 // isobuild.Trim(P1,P2);
 	  tabP.Append(P1);
@@ -236,8 +240,13 @@ void StdPrs_WFDeflectionRestrictedFace::Add
   FFaceTimer2.Start();
 #endif
 
+  // Compute the hatching tolerance.
+  aHatchingTol *= 0.1;
+  aHatchingTol = Max(Precision::Confusion(), aHatchingTol);
+  aHatchingTol = Min(1.e-5, aHatchingTol);
+
   // load the isos
-  Hatch_Hatcher isobuild(1.e-5,ToolRst.IsOriented());
+  Hatch_Hatcher isobuild(aHatchingTol, ToolRst.IsOriented());
   Standard_Boolean UClosed = aFace->IsUClosed();
   Standard_Boolean VClosed = aFace->IsVClosed();
 
diff --git a/src/ViewerTest/ViewerTest.cxx b/src/ViewerTest/ViewerTest.cxx
index 47980f3f3c..e837cd4a34 100755
--- a/src/ViewerTest/ViewerTest.cxx
+++ b/src/ViewerTest/ViewerTest.cxx
@@ -55,8 +55,10 @@
 #include <Aspect_InteriorStyle.hxx>
 #include <Graphic3d_AspectFillArea3d.hxx>
 #include <Graphic3d_TextureRoot.hxx>
+#include <Graphic3d_AspectLine3d.hxx>
 #include <Image_AlienPixMap.hxx>
 #include <Prs3d_ShadingAspect.hxx>
+#include <Prs3d_IsoAspect.hxx>
 
 #ifdef HAVE_CONFIG_H
 # include <config.h>
@@ -90,6 +92,7 @@ extern int ViewerMainLoop(Standard_Integer argc, const char** argv);
 #define DEFAULT_COLOR    Quantity_NOC_GOLDENROD
 #define DEFAULT_MATERIAL Graphic3d_NOM_BRASS
 
+
 //=======================================================================
 //function : GetColorFromName
 //purpose  : get the Quantity_NameOfColor from a string
@@ -578,6 +581,122 @@ void ViewerTest::StandardModeActivation(const Standard_Integer mode )
   }
 }
 
+//==============================================================================
+//function : CopyIsoAspect
+//purpose  : Returns copy Prs3d_IsoAspect with new number of isolines.
+//==============================================================================
+static Handle(Prs3d_IsoAspect) CopyIsoAspect
+      (const Handle(Prs3d_IsoAspect) &theIsoAspect,
+       const Standard_Integer theNbIsos)
+{
+  Quantity_Color    aColor;
+  Aspect_TypeOfLine aType;
+  Standard_Real     aWidth;
+
+  theIsoAspect->Aspect()->Values(aColor, aType, aWidth);
+
+  Handle(Prs3d_IsoAspect) aResult =
+    new Prs3d_IsoAspect(aColor, aType, aWidth, theNbIsos);
+
+  return aResult;
+}
+
+//==============================================================================
+//function : visos
+//purpose  : Returns or sets the number of U- and V- isos and isIsoOnPlane flag
+//Draw arg : [name1 ...] [nbUIsos nbVIsos IsoOnPlane(0|1)]
+//==============================================================================
+static int visos (Draw_Interpretor& di, Standard_Integer argc, const char** argv)
+{
+  if (TheAISContext().IsNull()) {
+    di << argv[0] << " Call 'vinit' before!\n";
+    return 1;
+  }
+
+  if (argc <= 1) {
+    di << "Current number of isos : " <<
+      TheAISContext()->IsoNumber(AIS_TOI_IsoU) << " " <<
+      TheAISContext()->IsoNumber(AIS_TOI_IsoV) << "\n";
+    di << "IsoOnPlane mode is " <<
+      (TheAISContext()->IsoOnPlane() ? "ON" : "OFF") << "\n";
+
+    return 0;
+  }
+
+  Standard_Integer aLastInd = argc - 1;
+  Standard_Boolean isChanged = Standard_False;
+  Standard_Integer aNbUIsos;
+  Standard_Integer aNbVIsos;
+
+  if (aLastInd >= 3) {
+    Standard_Boolean isIsoOnPlane = Standard_False;
+
+    if (strcmp(argv[aLastInd], "1") == 0) {
+      isIsoOnPlane = Standard_True;
+      isChanged    = Standard_True;
+    } else if (strcmp(argv[aLastInd], "0") == 0) {
+      isIsoOnPlane = Standard_False;
+      isChanged    = Standard_True;
+    }
+
+    if (isChanged) {
+      aNbVIsos = Draw::Atoi(argv[aLastInd - 1]);
+      aNbUIsos = Draw::Atoi(argv[aLastInd - 2]);
+      aLastInd -= 3;
+
+      di << "New number of isos : " << aNbUIsos << " " << aNbVIsos << "\n";
+      di << "New IsoOnPlane mode is " << (isIsoOnPlane ? "ON" : "OFF") << "\n";
+
+      TheAISContext()->IsoOnPlane(isIsoOnPlane);
+
+      if (aLastInd == 0) {
+        // If there are no shapes provided set the default numbers.
+        TheAISContext()->SetIsoNumber(aNbUIsos, AIS_TOI_IsoU);
+        TheAISContext()->SetIsoNumber(aNbVIsos, AIS_TOI_IsoV);
+      }
+    }
+  }
+
+  Standard_Integer i;
+
+  for (i = 1; i <= aLastInd; i++) {
+    TCollection_AsciiString name(argv[i]);
+    Standard_Boolean IsBound = GetMapOfAIS().IsBound2(name);
+
+    if (IsBound) {
+      const Handle(Standard_Transient) anObj = GetMapOfAIS().Find2(name);
+      if (anObj->IsKind(STANDARD_TYPE(AIS_InteractiveObject))) {
+        const Handle(AIS_InteractiveObject) aShape =
+        Handle(AIS_InteractiveObject)::DownCast (anObj);
+        Handle(AIS_Drawer) CurDrawer = aShape->Attributes();
+        Handle(Prs3d_IsoAspect) aUIso = CurDrawer->UIsoAspect();
+        Handle(Prs3d_IsoAspect) aVIso = CurDrawer->VIsoAspect();
+
+        if (isChanged) {
+          CurDrawer->SetUIsoAspect(CopyIsoAspect(aUIso, aNbUIsos));
+          CurDrawer->SetVIsoAspect(CopyIsoAspect(aVIso, aNbVIsos));
+          TheAISContext()->SetLocalAttributes
+                  (aShape, CurDrawer, Standard_False);
+          TheAISContext()->Redisplay(aShape);
+        } else {
+          di << "Number of isos for " << argv[i] << " : "
+             << aUIso->Number() << " " << aVIso->Number() << "\n";
+        }
+      } else {
+        di << argv[i] << ": Not an AIS interactive object!\n";
+      }
+    } else {
+      di << argv[i] << ": Use 'vdisplay' before\n";
+    }
+  }
+
+  if (isChanged) {
+    TheAISContext()->UpdateCurrentViewer();
+  }
+
+  return 0;
+}
+
 //==============================================================================
 //function : VDispAreas,VDispSensitive,...
 //purpose  : Redraw the view
@@ -3373,6 +3492,10 @@ void ViewerTest::Commands(Draw_Interpretor& theCommands)
   const char *group = "AIS_Display";
 
   // display
+  theCommands.Add("visos",
+                  "visos [name1 ...] [nbUIsos nbVIsos IsoOnPlane(0|1)]\n"
+                  "\tIf last 3 optional parameters are not set prints numbers of U-, V- isolines and IsoOnPlane.\n",
+		  __FILE__, visos, group);
 
   theCommands.Add("vdisplay",
 		  "vdisplay         : vdisplay2 name1 [name2] ... [name n] ",
diff --git a/tests/bugs/vis/bug23705 b/tests/bugs/vis/bug23705
new file mode 100755
index 0000000000..c5c35cbaa2
--- /dev/null
+++ b/tests/bugs/vis/bug23705
@@ -0,0 +1,22 @@
+puts "========"
+puts "CR23705"
+puts "========"
+puts ""
+###############################################################
+## Isoline in the AIS viewer is not trimmed
+###############################################################
+
+restore [locate_data_file bug23705_plancher20igs_face.brep] result
+
+vinit
+visos 10 10 1
+
+vdisplay result
+vfit
+
+set x 326
+set y 295
+
+checkcolor $x $y 0 0 0
+
+set only_screen 1